Statistics

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.

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 taller than 74 inches?

• 2.5%
• 5%
• 16%
• 1%

The distribution of heights of adult American men is approximately Normal with mean 69 inches and standard deviation 2.5 inches. Between what heights do the middle 95% of men fall? 

• 66.5-71.5
• 64-74
• 61.5-76.5
• 65-73

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%