Ch. 2 ~ AP Stats

for the density curve below, which of the following is true?

A. the median is 0.5

B. the median is larger than 0.5

C. the density curve is skewed right

D. the density curve is normal

E. the density curve is symmetric

B. the median is larger than 0.5

use figure 1-1. for this density curve, what percent of the observations lie above 4?

A. 20%

B. 25%

C. 50%

D. 75%

E. 80%

A. 20%

you can roughly locate the mean of a density curve by eye because it is…

A. the point at which the curve would balance if made of solid material

B. the point that divides the area under the curve into two equal parts

C. the point at which the curve reaches its peak

D. the point where the curvature changes direction

E. the point at which the height of the graph is equal to 1

A. the point at which the curve would balance if made of solid material

the density curve below shows the distribution of a variable that takes values from 0 to 1. what percent of the observations lie between 0 and 0.5?

A. 20%

B. 25%

C. 50%

D. 75%

E. 80%

B. 25%the

the 35th percentile of a population is the number x such that…

A. 35% of the population scores are above x

B. 65% of the population scores are above x

C. 35% of the population scores equal x

D. x is 35% of the population median

E. x is 35% of the population mean

B. 65% of the population scores are above x

a score’s percentile is a measure of…

A. center

B. spread

C. relative location

D. skew

E. relative frequency

C. relative location

consider the following cumulative relative frequency graph of the scores of students in an introductory statistics course: \[insert graph\]

a grade of C or C+ is assigned to a student who scores between 55 and 70. the percentage of students who obtained a grade of C or C+ is…

A. 15%

B. 20%

C. 25%

D. 30%

E. 50%

B. 20%a

a standard score describes…

A. how much skew there is in a distribution

B. how much spread there is in a distribution

C. how far apart the mean and median of a distribution are

D. how far a particular score is from the mean

E. how far a particular score is from the median

D. how far a particular score is from the mean

the mean number of days that the midge Chaoborus spends in its larval stage is 14.1 days, with a STD of 2.2 days. this distribution is skewed toward higher values. what is the z-score for an individual midge that spends 12.7 days in its larval stage?

A. -1.11

B. -0.64

C. 0.64

D. 0.94

E. none of these, because z-score cannot be used unless the distribution is normal

B. -0.64

ramon is planning on buying a new car. here’s the stats:

ford escape: sport utility vehicle, 28 miles per gallon, mean fuel efficiency is 23, STD is 7.6

ford fusion: mid-sized sedan, 31 miles per gallon, mean fuel efficiency is 27, STD is 5.2

which vehicle has a better standing, relative to others of the same style?

A. ford fusion sedan has a better relative standing, because it’s z-score is higher

B. ford fusion sedan has a better relative standing, because it’s z-score is closer to 0

C. ford escape SUV has a better relative standing, because it’s z-score is higher

D. ford escape SUV has a better relative standing, because it’s z-score is closer to 0

E. we can’t make any comparisons unless we know that the distribution of fuel efficiency for vehicle types is normally distributed

A. ford fusion sedan has a better relative standing, because it’s z-score is higher

if 30 is added to every number on a list, the only one of the following that is not changed is…

A. the mean

B. the mode

C. the 75th percentile

D. the median

E. the STD

E. the STD

a sample was taken of the salaries of 20 employees of a large company. the following are the salaries (in thousands of dollars) for this year.

28, 31, 34, 35, 37, 41, 42, 42, 42, 47, 49, 51, 52, 52, 60, 61, 67, 72, 75, 77

suppose each employee in the company receives a $3,000 raise for the next year.

use scenario 2-1. the median salary for the company will…

A. be unchanged

B. increase by $3,000

C. be multiplied by $3,000

D. increase by square root of $3,000

E. increase by $150

B. increase by $3,000

a sample was taken of the salaries of 20 employees of a large company. the following are the salaries (in thousands of dollars) for this year.

28, 31, 34, 35, 37, 41, 42, 42, 42, 47, 49, 51, 52, 52, 60, 61, 67, 72, 75, 77

suppose each employee in the company receives a $3,000 raise for the next year.

use scenario 2-1. the interquartile range of the salaries for the employees will…

A. be unchanged

B. increase by $3,000

C. be multiplied by $3,000

D. increase by square root of $3,000

E. decrease by $3,000

A. be unchangedthe

the normal curve below describes the death rates per 100,000 people in developed countries in the 1990’s. \[insert curve\]

the mean and STD of this distribution are approximately…

A. mean=100; STD=65

B. mean=100; STD=100

C. mean=190; STD=65

D. mean=190; STD=100

E. mean=200; STD=130

C. mean=190; STD=65

items produced by a manufacturing process are supposed to weigh 90 grams. the manufacturing process causes variability in the items produced and they do not all weigh exactly 90 grams. the distribution of weights can be approximated by a normal distribution with mean 90 grams and STD of 1 gram. about what percentage of the items will either weigh less than 87 grams or more than 93 grams?

A. 0.15%

B. 0.3%

C. 6%

D. 94%

E. 99.7%

B. 0.3%

birthweights at a local hospital have a normal distribution with a mean 110 oz and a STD of 15 oz. the proportion of infants with birthweights between 125 oz and 140 oz is about…

A. 0.136

B. 0.270

C. 0.477

D. 0.636

E. 0.819

A. 0.136

IQs among undergraduates at mountain tech are approximately normally distributed. the mean undergraduate IQ is 110. about 99% of undergraduates have IQs between 100 and 120. the STD of these IQs is about…

A. 5

B. 10

C. 15

D. 20

E. 25

A. 5

using the standard normal distribution tables, the area under the standard normal curve corresponding to Z< 1.1 is…

A. 0.1357

B. 0.2704

C. 0.8413

D. 0.8438

E. 0.8643

E. 0.8643

using the standard normal distribution tables, the area under the standard normal curve corresponding to -0.5 < Z < 1.2 is…

A. 0.2815

B. 0.3085

C. 0.3661

D. 0.5764

E. 0.8849

D. 0.5764

the scores on a university exam are normally distributed with a mean of 62 and a STD of 11. if the bottom 5% of students will fail the course, what is the lowest rank that a student can have and still be awarded a passing grade?

A. 40

B. 43

C. 44

D. 57

E. 62

E. 62

a company produces packets of soap power labeled “giant size 32 ounces.” the actual weight of soap powder in a box has a normal distribution with a mean of 33 oz and a STD of 0.8 oz. what proportion of packets are underweight (weigh less than 32 oz)?

A. 0.106

B. 0.115

C. 0.159

D. 0.212

E. 0. 841

A. 0.106

the time to complete a standardized exam is approximately normal with a mean of 70 minutes and a STD of 10 minutes. how much time should be given to complete the exam so that 80% of the students will complete the exam in the time given?

A. 61.6 minutes

B. 78.4 minutes

C. 79.8 minutes

D. 84 minutes

E. 92.8 minutes

B. 78.4 minutes

suppose that scores on a certain IQ test are normally distributed with mean 110 and STD 15. then about 40% of the scores are between…

A. 80 and 140

B. 65 and 155

C. 106 and 110

D. the 25th and 75th percentiles

E. 102 and 118

E. 102 and 118

you are chatting with the principal of a high school. the principal says that SAT scores are normally distributed. she doesn’t remember the mean or STD, but she does remember that the upper and lower quartiles are 500 and 600. the STD of SAT verbal scores is closest to…

A. 25 points

B. 50 points

C. 75 points

D. 100 points

E. 550 points

C. 75 points

a stemplot of a set of data is roughly symmetric, but the data do not even approximately follow the 68-95-99.7 rule. we conclude that the data are…

A. normal, but not standard normal

B. standard normal

C. not normal

D. normal

E. skewed in both directions

C. not normal

the plot shown below is a normal probability plot for the total annual cost (tuition plus room and board) to attend 126 of the top colleges in the country in 2005. which statement is true for these data?

A. the data are clearly normally distributed

B. the data are approximately normally distributed

C. the data are clearly skewed to the left

D. the data are clearly skewed to the right

E. there is insufficient information to determine the shape of the distribution

C. the data are clearly skewed to the left