Normal Distribution Pre-Test

In a normal distribution, which of these would describe a proportion of .5?

• All z-scores between 1 and 2

• All z-scores greater than 0

• All z-scores greater than .5

• All z-scores between -3 and 3

Find a z-score that corresponds with 7cm if the mean is 3cm and the standard deviation is 2cm.

• z = 2

• z = 12

• z = 4

• z = 8

Find the z-score that corresponds to 5.4mm if the mean is 8mm and the standard deviation is 2.6mm.

• z = 1

• z = 2.6

• z = -1

• z = 5.2

Michelle got a z-score of -1.13. What do you know about the observation that this z-score came from?

• It was more than the mean

• It was less than the mean

• It was negative

• It was positive

Which would have the biggest proportion?

• P(z>0)

• P(z>-1)

• P(z<2)

• P(z>3)

According to the empirical rule, how much of the data falls within 3 standard deviations? 

• 25%

• 68%

• 95%

• 99.7%

At Thomas Nelson Community College, the Pre-Test for Mathematics has 200 points on the test. The mean is 120 and the standard deviation is 20. In order to pass the Mathematics Pre-Test, a student must score 140 points. If 360 freshmen took the pre-test last fall, how many failed?

• 200

• 240

• 302

• 324

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

• 25%

• 68%

• 95%

• 99.7%

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%

On his midterm exam, Jimmy scored 75 points, which was exactly 2 standard deviations above the mean. If the standard deviation for the test is 4, what is the mean for the test?

• 79

• 75

• 71

• 67