Statistics Chapter 3 Review

Relative Location

A score's percentile is a measure of

How far a particular score is from the mean.

A standard score describes

68-95-99.7

Empirical Rule

49.85%

For a Normal distribution with mean 20 and standard deviation 5, approximately what percent of the observations will be between 20 and 35?

2.5%

For a Normal distribution with mean 20 and standard deviation 5, approximately what percent of the observations will be less than 10?

50%

For a Normal distribution with mean 20 and standard deviation 5, approximately what percent of the observations will be less than 20?

79%

Here is a list of exam scores for Mr. Williams's calculus class: 60 61 61 65 72 75 75 78 81 81 85 89 91 98 What is the percentile of the person whose score was 85?

Compare the mean and median

One way of determining whether a data set roughly follows a Normal distribution is to

1.50

SAT scores are Normally distributed with mean 500 and standard deviation 100. Julie scores 650. Her standard score is

0.31

The 62nd percentile of a standard Normal distribution is approximately what z score?

the number with 70% of the data below it or equal to it

The 70th percentile of a distribution is

2.5%

The distribution of heights of adult men is approximately Normal with mean 69 inches and standard deviation 2.5 inches. About what percent of men are taller than 74 inches?

69.75

The distribution of heights of adult men is approximately Normal with mean 69 inches and standard deviation 2.5 inches. How tall is a man whose standardized height is 0.3?

38.21%

The distribution of heights of adult men is approximately Normal. A man whose standardized height is 0.3 is at the 61.79th percentile. What percent of all men are taller than he is?38

Median

The half area point of a curve

92cm

The heights of three-year-old boys are Normally distributed with a mean of 96 cm. and a standard deviation of 4.5 cm. What is the height of a boy who is in the 20th percentile?

9th Percentile

The heights of three-year-old boys are Normally distributed with a mean of 96 cm. and a standard deviation of 4.5 cm. What is the percentile of a three-year-old boy who is 90 cm. tall?

34.5%

The lifespan of all microwave ovens is Normally distributed with a mean of 9 years and a standard deviation of 2.5 years. What percentage of microwave ovens last more than 10 years?

6.28

The mean age (at inauguration) of all U.S. Presidents is approximately Normally distributed with a mean of 54.6. Barack Obama was 47 when he was inaugurated, and his z score was -1.21. What is the standard deviation of presidents' ages?

Mean

The measure that is pulled towards the tail in a skewed distribution.

8.08%

The percentage of scores in a standard Normal distribution that are below -1.4 is:

48.21%

The percentage of scores in a standard Normal distribution that are between -2.1 and 0 is:

309

There are 1000 coins in a box, and their weights are Normally distributed with mean 11 grams and standard deviation 2 grams. About how many coins weigh more than 12 grams?

z-score and percentile

Two methods of describing relative location of scores within a distribution are:

Mean

The balancing point of a curve