Empirical Rule

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%

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

• 34%

• 81.5%

• 16%

• 2.5%

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score between 68 and 82

• 11

• 2

• 340

• 498

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score higher than 68?

• 11

• 12

• 420

• 250

The distribution of heights of adult American men is approximately Normal with mean 69 inches and standard deviation 2.5 inches. What percent of men are between 64 and 66.5 inches tall? 

• 50%

• 2.5%

• 13.5%

• 34%

The heights of male students are Normally distributed with mean 1.8 m and standard deviation 0.2 m

In a population of 400 male students, how many would you expect to have a height between 1.4 m and 1.6 m?

• 13.5

• 54

• 97

• 100

According to the 68-95-99.7 rule, what percentage of data falls within one standard deviation of the mean in a normal distribution?

• 50%

• 68%

• 75%

• 90%

In a normal distribution, what percentage of data falls within two standard deviations of the mean according to the 68-95-99.7 rule?

• 50%

• 95%

• 99.7%

• 68%

In a normal distribution, what percentage of data falls within three standard deviations of the mean according to the 68-95-99.7 rule?

• 68%

• 95%

• 50%

• 99.7%

500 juniors at Central High School took the ACT last year. The scores were distributed normally with μ=24 and σ=4.

What percent of ACT scores are between 20 and 28?

• 34%

• 68%

• 81.5%

• 95%