Probability Distributions

The 75th percentile is also know as the

• median

• third quartile

• 1st quartile`

• interquartile range

Given a mean of 75 and a standard deviation of 7, what percentage of scores are between 75 and 82?

• 68%

• 81.5%

• 16%

• 34%

The average weight of a newborn is 7.5 pounds, with a standard deviation of 1.25 pounds. Birth weight follows the standard normal curve. What percent of newborns weigh 5 pounds or less at birth?

• 2.35%

• 0.15%

• 2.5%

• 50%

The shelf life of a particular dairy product is normally distributed with a mean of 12 days and a standard deviation of 3 days.

About what percent of the products last between 12 and 15 days?

• 68%

• 34%

• 16%

• 2.5%

If this is the graph of data normally distributed with a mean of 30 and a standard deviation of 5, what label (number) is written at the blue circle?

• 20

• 15

• 40

• 30

If this is the graph of data normally distributed with a mean of 30 and a standard deviation of 5, what label (number) is written at the blue circle?

• 40

• 35

• 45

• 50

What shape is a normal distribution curve?

• Half curve

• Round curve

• Bell curve

• Square curve

The normal curve is symmetrical about the mean.

• True

• False

According to the empirical rule, what percentage of data falls within 1 standard deviation of the mean?

• 25%

• 68%

• 95%

• 99.7%

According to the empirical rule, how much of the data falls within 2 standard deviations of the mean?

• 25%

• 68%

• 95%

• 99.7%