Normal Distribution Skills Check

The normal curve is symmetrical about the mean.

• True

• False

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

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%

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%

The area under the normal curve is 1.

• True

• False

Company pack coffee in bags marked as 250 g. A large number of packs of coffee were weighed and the mean and standard deviation were calculated as 255 g and 2.5 g respectively. Assuming this data is normally distributed, what percentage of packs are underweight?

• 2.5%

• 3.5%

• 4%

• 5%

The ages of the population of people living in Meru area in Ipoh are Normally distributed with mean 43 and standard deviation 14

The town has a population of 5,000.

How many would you expect to be aged between 22 and 57?

You can use this Standard Normal Distribution curve:

• 1750

• 3860

• 3870

• 4330

68% of the marks in a test are between 51 and 64 Assuming this data is normally distributed, what are the mean and standard deviation?

• Mean = 57

  S.D. = 6.5

• Mean = 57

  S.D. = 7

• Mean = 57.5

  S.D. = 6.5

• Mean = 57.5

  S.D. = 13