AP Stats MCQ question and answers

in an experiment, an observed effect is so larger regular or occurred by chance

statistically significant

if you buy one ticket in the lottery, then the probability that you win, a prize is .11 given the nature of the lottery the probability of winning is independent month-to-month if you buy one to get each month for five months, what is the probability that you lose, at least one prize

.44

The distribution of time it takes for different people to solve the certain crossword puzzle is strongly skewed to the right with the meaning of 30 minutes in standard deviation of 15 minutes, the distribution of Z scores for those times

skew to the right with the mean 30 and standard deviation of 15

start a random integer from -100 to 100 which of the following pairs of events are mutually exclusive (disjointed)?

A: The number above 50 B: the number that is less than 20

if you score on a test at the 60th percentile, you know your score lies

between the median and the third quartile

The central limit theorem refers to which of the following characteristics of the sampling distribution of the sample mean?

regardless of the shape of the populations distribution the sampling distribution of the mean from significantly larger samples will be approximately normal distributed

In some courses, students are graded on a normal curve, for example students within plus -.5 senior standard deviations of the mean receive a C between .5 and 1.0 standard deviations above the mean receive a C+ between 1.0 and 1.5 standard deviations about the mean receive a B minus within a standard deviation of 10 the bond for a B minus grade in the percent of students who will receive a B minus grade if the marks are actually normal distributed are?

(70,75), 9.19%

A rocket concert producer has scheduled an outdoor concert. if it is warm that day, she expect to make a $20,000 profit. If it is cold that day, she expects to make a $5,000 profit. If it's very cold that day, she expects to suffer a $12,000 loss. Based upon historical records, the weather office has estimated the chances of a warm day to be .60; the chances of a cold day to be .25. What is the producers expected profit?

$11,450

The best statistic for estimating a parameter has, which of the following characteristics?

low bias, low variability

using scenario 6-13. Which of the following is the approximate standard deviation of X?

19

use the scenario 6-13. Which of the following is mean of X?

600

there are 10 red marbles and eight green marbles in a jar. If you take three marbles from the jar (without replacement), the probability that they are all red is:

.147

other things being equal, large automobile, engines, consume, or fuel. You were planning an experiment to study the effects of engine size (in liters) on the gas mileage(in miles per gallon) of sport, utility vehicles. In this study,

gas mileage is a response variable, and you expect to find negative association

The way to male female students in class are summarized in the following boxplot: which of the following is not correct?

The male students have less variability than the female students

The probability of any outcome at random phenomenon is

The proportion of times the outcome occurs is very long series of repetitions

Medical researcher collects health data on many women in each of several countries. One of the variables measured for each woman in the study is her weight and pounds. The following list gives the five - number summary for the weight of adult woman in one of the countries about what percent of country a woman wait between 110 and 240 pounds?

75%

A student investigating study habits asks a simple random sample of 16 students in her school. How many minutes they spend on their English homework the previous night. Suppose the actual parameter values for this variable are mean = 45 minutes and standard deviation= 15 minutes. Which of the following best describes what we know about the sampling distribution of the means for the student sample?

mean of X= 45; standard deviation of X = 3.75; shape of the distribution unknown

which of the statements below about lease - squares regressions are correct. I switching the explanatory in response. Variables will not change the lease squares ration line to the slope of the line is very sensitive to outliers with large residuals. Three a value of R to the second power close to one does not guarantee that the relationship between the variables is linear

both 1 and 2 are correct

experience has shown that a certain eye detector will show a positive reading (indicates a lie) 10% of the time when a person is telling the truth and 95% of the time when a person is lying. Suppose that a random sample of five suspects is subjected to a lie detector test regarding a recent one person. Then the probability of observing no positive readings if all the suspects plead innocent, and are telling the truth

.591

according to the 1990 census, those states within above average number of people ask, who failed to complete high school tender have an above average of infant deaths, why. In other words, there is a positive association between XNY. The most possible explanation

lurking variables are probably present for example with large populations may have both larger number of people who don't complete high school and more infants

event a occurs with the probability of .2. The event be occurs with the probability of .8. if an and B are disjoint (mutually exclusive), then

P(A or B)= 1.0

if a distribution is skewed to the right, which of the following is true?

The mean must be greater than the median

The five number summary of four scores on the statistics exam is 11, 35, 61, 70, 79. In all, 380 students took the test. About how many has score scores between 35 and 61?

95

which of the following statements are true?

I and II

A sample of students opinions at the Big Ten university selects an SRS of 200 of the 30,000 undergraduate student students in separate SRS of the 100 of the 5000 graduate student. This kind of sample is called a

stratified random sample

which of these variables is least likely to have a normal distribution

annual income for all 150 employees at a local high school

which of the following is a true statement?

an important difference between binomial and geometric random variables is that there is a fixed number of trials in a binomial setting, and the number of trials varies in a geometric setting.

which of the following random variables geometric

The number of digits, I will read beginning at a random selected starting point in the table of random digits until I find the 7.

of people who died in the United States in a recent year, 86% were white, 12% we're black, and 2% were Asian. Diabetes causes 2.8% of deaths among white, 4.4% among blacks, and 3.5% amongst Asian. The probability that a randomly choosing death was due to di diabetes is about?

.030

if we took a SRS of 1700 people from California(population 34 million) and an SRS of 1000 people from Detroit (population of 1 million) which sampling distribution would have the smaller standard deviation?

California, because the sampling size(1700) is larger than Florida Detroit(1000)

A small company estimating it photocopy expenses find that the main number of copies made per day for the past 12 months is 258 copies per day with a standard deviation of 24 copies per day. Which of the following is a correct interpretation of the standard deviation?

on average, the number of cities made each day was about 24 copies per day away from the, 258

mr. Yates pick up a dozen items in the grocery store with the main cost of $3.25. Then he added an apple pie for $6.50. The new need for all 13 items is?

$3.50

The main speed of vehicles in the cars only lanes of the New Jersey Turnpike is 68 mph. The main speed of vehicles in the any vehicle lane is 64 mph. What must be true about the main speed of all of vehicles on the turnpike, assuming these are the only types of lanes?

it could be any number between 64 and 68 mph

The sampling distribution of statistic is?

The distribution of values taken by statistic and all possible samples of the large sample size from the same population

use scenario 3-15. Joseph is 22.5 months old. What is his predicted height?

79.11

Will 18 sided die 10 times the probability of getting exactly 3 sevens in those 10 rolls is given by?

(10/3)x(1/8)^3x(7/8)^7

The distribution of height of a student in a large class is roughly normal. Moreover, the average height is 68 inches, and approximately 95% of the height are between 62 and 74 inches. Thus, the standard deviation of the height distribution is approximately equal to?

3

use scenario 5-13. You select one student from this group at random. Which of the following statements is true about the events "typically walk to school "and "junior? "

The events are not mutually exclusive, but they are independent.

use scenario 5-13. You select one student from this group at random. If the student says he is a junior, what is the probability that he walks to school?

.160

if a = result of a single role of six - sided die and B = result of a single role of an eight sided die, then

mean equals 1, standard deviation equals the square root of 1.71+2.29

If PA. = 0.24 and PB. = 0.52 and A and B are independent, what is P(A or B)?

0.6352

if a statistic used to estimate a parameter is such that the mean of the sampling distribution is equal to the true value of the prime rib being estimated, what is the statistic said to be?

unbiased

use scenario 3-14. The lease squares regression line is the line that.

minimizes the sum of the squared residuals between the actual yield and the predicted yield

we wish to draw a sample of five without replacement from a population of 50 households. Suppose the households are numbered 01, 02,..., 50, and suppose that the relevant line of the random number table is. Then the household selected are?

household 11, 36, 23, 08, 42

A double blind experiment was conducted to evaluate the effectiveness of the salk polio vaccine. The purpose of keeping the diagnosing physicians ignorant of the treatment status of the experimental subject was to?

eliminate a possible source of bias

At least squares regression line for predicting weight of basketball players on the bias of their heights produced the residual plot below. What does the residual plot tell you about the linear model?

The curve pattern in the residual plot, suggest that the linear model is not appropriate

A public opinion pull in Ohio wants to determine whether or not registered voters in the state approved of Measure to be smoking and all public areas. They selected a simple random sample of 50 registered voters from each county in the stay and ask whether they approve or disapprove of the measure. This is an example of?

stratified random sample

you work for an advising agency that is preparing a new television commercial to appeal to women. You have been asked to design an experiment to complete compare the effectiveness of three versions of the commercial. Each subject will be shown one of the three versions and then ask her attitude toward the product. Do you think there may be large differences between women who are employed outside their home and those who are not. Because of those differences, you should use

A block design

The security system in a house has two units that set off an alarm when the motion is detected. Neither one is entirely reliable, but one or both always goes off when there is motion anywhere in the house. Suppose that for motion in a certain location, the probability that detector echo goes off and detector B does not go off is .25, and the probability that he does not go off is .35. What does the probability of B go off?

.75

Jun and Daron try applying for summer job at a local restaurant. After interviewing them, the restaurant owner says, "the probability that I hire jun is .7, and the probability that I hire deron is .4. The probability that I hire at least one of you is .9." What is the probability that both Jun and Deron get hired?

.2

which of the following properties is true for all normal density curbs?

1 and 2 only

when testing water for chemical impurities, results are often reported as VDL, that is, below detection limit. The following are the measurements of the amount of blood in a series of water samples taken from inner - city household (and parts per million): which of the following statements can be sure is true?

The median blood level in the water is 7 ppm

you draw two marbles at random from a jar that has 20 red marbles and 30 black marbles without replacement. What is the probability that both marbles are red?

.1551

in a town of Tower Hill, the number of cell phones in a household is a random variable W with the following distribution: the probability that a randomly selected household has at least two cell phone is?

.80

A bagel sugar manufacturer wants to estimate the average trunk diameter of a sugar maple tree in a large forest. There are too many trees to let them all and take a SRS, so he divides the force in several 110 m x 10 m plot, select 25 random, in measures the diameter of every sugar maple in each one. This is an example of?

a cluster sample

in order for the random variable, X to have a geometric distribution, which of the following conditions, most satisfy?

III AND IV

kitchen appliances don't last forever. The lifespan of all microwave ovens sold in the United States is approximately normal distribute it with a mean of nine years in the steam deviation of 2.5 years. What percentage of the oven was more than 10 years?

34.5%

an agricultural economic case says that the correlation between corn price and soy bean prices is R = .7. This means that?

when corn prices are above average soybean prices also tend to be above average

you have data for many families on the parents income, and the years of education their eldest child complete. Your initial examination of the data indicates that children from wealthy families tend to go to school for a longer period when you make us scatter plot,

The explanatory variable is parents income, and you expect to see a positive association

what is distribution of values taken by a statistic and all possible samples of the same size from the same population called?

The sampling distribution of the statistic

A fire department in a rule county reports that it's response. Time to fires is approximately normally distributed with a mean of 22 minutes in a standard deviation of 11.9 minutes. Approximately what proportion of their response times is over 30 minutes?

.25

A fair coin is tossed 4 times, and each time the queen lands heads up. Is a coin is tossed 1996 more times, how many heads are most likely to appear in these 1996 additional tosses?

998

The cumulative relative frequency graph below shows the distribution of length(in centimeters) of fingerlings at a fish hatchery. The interquartile range for this distribution is approximately:

1.2 cm

let the random variable act represent the amount of money. Dan makes doing volunteer in a random selected week in the summer. Assume that exit is normal with the mean of $240 in a standard deviation of $60. The probability is approximately .6 that, and a random selected week, Dan will make less than

$255

for the histogram below, what is the proper ordering of the mean and medium? Note that the graph is not numerically precise - only the relative positions are important.

One is the mean and two is the median

find a dramatic drop of 500 points in the Dow Jones industrial average in September 1998, a pool conducted for the association press found that 92% of those poles said that a year from now their families financial situations will be as good as it is today or better. Which of the following terms subscribe the numbers 92%?

statistic

let the random variable act represent represent the profit made on a randomly selected day by a certain store. Assume that X is normal with a mean of $360 and a senior deviation of $50. What is the P(X greater than $400)?

.2119

A coffee machine dealer has a data on the number of copying machines at each of 89 customer locations and the number of service calls a month. Why at each location. Summary calculations give X line = 8.4, Sx = 2.1, Y line = 14.2,sy equal 3.8, and r equal 8.6. What is the slope of the least squared regression line of the number of service calls on the number of copies?

1.56

A materials and engineer wishes to compare the distribution of two different types of paying material. She has 40 different 1 mile stretches of interstate highway that she's been authorized to repay for this study. She decides to carry out a match pair experiment. Which of the following is the best way for her to carry out the randomization for the study?

what each of the 40 roads act as its own pair, dividing each road into the first half mile and then the second half mile. Flip a coin for each of the 40 Year Rd. ways to decide which half mile gets which pave

to test the effect of music on activity, a group of assembly line workers are given portable MP3 players to play whatever music they choose while working for one month. For another month, they work without music. The order of the two treatments for each worker is determined randomly. This is.

A match pair experiment

you take a sample of a size 25 from very large public obligation in which true population is P = .1, this violating the conditions that NP is greater than or equal to 10 and the DN(one minus P) greater than or equal to 10. Which statement below best describes what you know about the sampling distribution of P hat?

The mean is .1 singular deviation is the square root of .1×.9÷25 distribution is approximately normal

A small company that prints custom T-shirts has six employees, one of whom is the owner and manager. Suppose the owner makes $120,000 per year and the other employee makes between $40,000 and 50,000 per dollars per year. One day, the owner decides to give himself a $30,000 raise. Which of the following describes how the companies mean salaries would change?

The main word increased by $5000 and the medium would not change

in a statistics course, a linear regression equation was competed to predict the final exam score of the score on the first test. The equation was Y equals 10+.9 X where why is the final exam score and ex is is going on the first text, Carla scored 95 on her first test what is the predicted value of our score on the final exam?

95.5

The variance of the sum of two random variables x and y is

σx^2 + σy^2 only if X and Y are independent.

Control groups are used in experiment in order to

Control the effects of outside variables on the outcome

A new headache remedy was given to a group of 25 subjects who had headaches. Four hours after after taking the new remedy, 20th subjects reported that their headaches has disappeared. From this information information you can conclude

nothing because there is no control group for comparison

A set of data describes relationship between the size of an annual salary raises in the performance ratings for employees of certain company. The lease squares regression equation is Y equals = 1400+2000X where why is the race amount in dollars and access the performance rating. Which of the following statements is not necessarily true?

The actual relationship between sailor raises and performance rating is linear

people would type O negative blood are universal donors. That is, any patient can receive a transfusion of negative blood. Only 7.2% of American population has own negative blood. If 10 people appear at random to give blood, what is the probability that at least one of them is a universal donor?

.526

A vending machine operator has determined that the number of candy bar is sold per week by a certain machine is a random variable with a meaning of 125 in the standard deviation in the seven. His profit for each bar sold is $.25, and it cost him five dollars per day to maintain the machine and rent the space for it. What are the mean and standard deviation for Y equal the profit he earns from this machine in a randomly selected week.?

mean=26.25, standard deviation =$1.75

The graph lobe is a normal probability plot for the amount of rainfall obtained from 26 randomly selected clouds that were seated with silver oxide. Which of the following statements about the shape of the rainfall distribution is true.?

The distribution is skewed, right

The reason that blocking as a randomized block design is sometimes use an experiment is to

reduce variability arising from random assignment

if a store runs out of advertising material during a sale, customers become upset, in the store is not only the sale, but also Goodwill. From past experience, a music store finds that the mean number of CDs sold in a sale is 845, the standard deviation is 15, and in a histogram of the demand is approximately normal. The manager is willing to accept a 2.5% chance of the seas will be sold out. About how many CDs should the manager order for an upcoming sale?

860

in a setting of a previous problem, about what percent of the variation in the number of service calls is explained by the linear relation between number of service calls, and the number of machines? Given R = .86?

74%

which of the following is a method for improving their accuracy of a sample?

use large sample size

A friend has placed a large number of plastic disks in a hat and invited you to select one at random. He informs you that they have numbers on them and that one of the following is the probability model for the number on the disk you have chosen. Which one is it?

(Chart) No1,2,3,4,5 Prob. .1,.2,0,.3,.4

The 16th percentile of a normal distributed variable as a value of 25 and the 97.5 percentile has the value of 40. Which of the following is the best estimate of the mean standard deviation of the variable?

mean equals 30 standard deviation equals five

let the random variable act represent the weight of male black bears before they begin hibernation. Research has shown that X is approximately normal distributed with a mean of 250 pounds in a scenery deviation of 50 pounds. What is P(X greater than 325 pounds)?

.0668

A dealer in the sand casino in Las Vegas selects 40 cards from the standard deck of 52 cards. Y be the number of red cards and the 40 cards selected. Which of the following best describes this setting?

y has a binomial distribution with an equal 40 observations in the probability of success P equals .5, provided that after selecting a card is replaced in the deck, and the deck is shuffled well before the next car is select

in a large population of college students, 20% of the students have experienced feeling of math anxiety. If you take a random sample of 10 students from this population, the main insanity deviation of the number of students in the sample who have experienced math anxiety is.

mean equals 2; standard deviation equals 1.265

yeah, a school with 600 students, 25% of them walk to school each day. If we choose a random sample of 40 students from the school, it is appropriate to model the number of students in our sample who walked to school with a binomial distribution where N equals 40 and P equals .25?

yes, because the sample size is less than 10% of the population size

The income in a certain certain large population of college teachers have a normally distribution with a mean of $60,000 in a standard deviation of $5000. Four teachers are selected at Rando from this population to serve on a salary review committee. What is the probability that on average salary exceeds $65,000

.0228

in order to use the formula standard deviation of X equals standard deviation over the square root of N2 calculate the standard divisions of sampling distribution of the sample mean which of the following conditions

three only

A stratified, random sample addresses, the same issues at which of the following experimental designs?

A block design

A college basketball player makes 80% of her free throws. At the end of the game, her team is losing by two points. She is fouled attempting a three-point shot and is awarded three free throws. Assuming free throws attempts are independent, what is the probability that she makes at least two of the free throws?

.896

use the information in the previous problem. About what percentage of men are over 70.5 inches tall.

16

here are the IQ test scores of 10 randomly chosen fifth grade students: to make a stem plot of these scores you would use as a stem

09, 10, 11, 12, 13, and 14

Mr. nerdly ask the students to make him a piece statistics class to report their overall grade point average and their SAT math scores. The scatter pop below provide provides information about his student data. The dark line is the least squares regression line for the data, and the equation is Y equals 410.54+67.3 X. Which of the following statements about the circled point is false?

The students residual is negative

an experiment to measure the effect of giving growth hormones to girls, affected by toners syndrome, was carried out recently in Vancouver. All 34 girls in the study were giving the growth hormone, and their heights were measured at the time the hormone was given and again one year later. No measurements were made on their final adult height. Which of the following is not a problem with the experiment

non-response bias

The height of American men age 18 to 24 approximately normally distributed with a mean of 68 inches and the standard deviation of 2.5 inches. Only about 5% of young men have heights outside of the range?

63 inches to 73 inches

A nutritionist monster study effective storage time on the amount of vitamin C present in freeze dry fruit when stored for 612 and 18 months of time vitamin C is measured in milligrams for 100 mg of fruit. Six fruit packs were randomly assigned to each of the three storage times. The treatment, experimental unit, and response are repetitively:

A specific storage time, a fruit pack, amount of vitamin C