Week 5 Word Problems and Examples

Given z score find probability

Use normalcdf

Given probability find z score

Use invNorm

Given probability find x value

Use invNorm

Given x values find probability

Use normalcdf

Find area left of a value

Use normalcdf

Find area right of a value

1 - normalcdf result

Find probability between two values

Use normalcdf with lower and upper limits

Sample size increases what happens to standard error?

Standard error gets smaller

Sample size doubles what happens to spread

Spread decreases

Population is skewed n = 40 —> Sampling distribution is?

approximately normal

Population is NOT normal n = 50 —> What theory applies?

Central Limit Theorem

Population is normal n = 10 —> Means Sampling distribution is?

normal

Mean of sampling distribution if population mean is 80

80

Population mean is 42 sample mean center

42

Population standard deviation is used for

Standard error formula

Question asks how sample means vary

Use standard error

Question asks spread of sample means

Standard error

Question asks average of sample means

Population mean

Question asks all possible sample means

Sampling distribution

Question asks number of standard deviations from mean

z score

Calculator says probability calculator

normalcdf

Calculator says inverse calculator

invNorm

Find top ten percent score

Use invNorm

Find bottom twenty percent score

Use invNorm

Find probability above x

1 - left area

Find probability below x

Use normalcdf

Find probability between x values

Use normalcdf

Find z score from ninety fifth percentile

Use invNorm

Find x value from eighty fifth percentile

Use invNorm

Large sample means look like

Normal distribution

Increasing sample size changes center

It does not change

Increasing sample size changes spread

It decreases

Increasing sample size changes shape

More normal