Mat 143 Statistics Empirical Rule

In a factory, the weight of the concrete poured into a mold by a machine follows a normal distribution with a mean of 1150 pounds and a standard deviation of 22 pounds. Approximately 99.7% of molds filled by this machine will hold weights in what interval? 

• 1084 to 1216 pounds 

• 1106 to 1150 pounds 

• 1106 to 1194 pounds 

• 1128 to 1172 pounds

The mean life of a tire is 30,000 km. The standard deviation is 2000 km.

Then, 68% of all tires will have a life between ___________ km and __________ km.

•  28,000 km and 32,000 km.

• 24,000 km and 34,000 km.

• 26,000 km and 34,000 km.

• 27,000 km and 31,000 km.

What percent of people within 3 standard deviations of the mean?

• 99.7

• 34

• 68

• 95

What percent of people within 2 standard deviations of the mean?

• 99.7

• 34

• 68

• 95

When Julia goes bowling, her scores are normally distributed with a mean of 200 and a standard deviation of 14. Using the empirical rule, what percentage of the games that Julia bowls does she score between 158 and 242?

When Avani goes bowling, her scores are normally distributed with a mean of 145 and a standard deviation of 12. Using the empirical rule, determine the interval that would represent the middle 68% of the scores of all the games that Avani bowls.

Scores on a certain standardized test have a mean of 500, and a standard deviation of 100. How common is a score between 600 and 700? Calculate the probability. 

• 2.5%

• 2.35%

• 16%

• 13.5%

What percent of people within 1 standard deviation of the mean?

• 99.7

• 34

• 68

• 95

What percentage of the data is between 1 and 2 standard deviations

• 34%

• 50%

• 2.35%

• 13.5%

What percent of people are 3 standard deviations above the mean?

• .15

• 34

• 68

• 2.35