The average age of CEO’s is 56 years. The distribution of ages is normally distributed, and the standard deviation is 4 years.
Find the proportion of CEO’s who are between 56 and 60 years old.
Find the proportion of CEO’s who are over 51 years old.
Find the probability a CEO is between 58 and 65 years old.
The average life of a brand of automobile tires is 30,000 miles, and the standard deviation is 2,300 miles. The distribution of lifespans is normal.
What is the probability a tire will last more than 35,000 miles?
The manufacturer wants to choose a warranty so that 3% of all tires will need to be replaced while under warranty. How long should the warranty be (in miles)?
The scores on a test are normally distributed with a mean of 130 and a standard deviation of 20. A personnel manager will only hire people whose scores are in the top 75% of all scores. What is the lowest score a person could get on this test and be eligible to be hired by this manager?