STT 2820 - Normal Distribution (Ch 5)

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Using the empirical rule:

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.

Using the 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 95% of molds filled by this machine will hold weights in what interval?

The average waist size for teenage males is 29 inches with a standard deviation of 1.4 inch.

If waist sizes are normally distributed, estimate the proportion of teenagers who will have waist sizes less than 31 inches?

The weights of paper discarded each week by households are normally distributed with a mean of 9.43 pounds and a standard deviation of 4.17 pounds.

What percent of households discard between 10 and 12 pounds?

Heights of women are normally distributed with a mean of 63.6 inches and a standard deviation of 2.5 inches. The Beanstalk Club, a social organization for tall people, has a requirement that women must be at least 70 inches tall.

What percentage of adult women meets the requirement to join the club?

The lengths of human pregnancies are normally distributed with a mean of 268 days and a standard deviation of 15 days.

The longest 25% of pregnancies will last at least ___ days.

Commute times during rush hour to get through the town of Boone can be based on the model N(18,4).

What are the cutoff values for the the middle 50% of commutes during rush hour in Boone?

Find the percent of the standard Normal model found in the given region.

z < 1.38