1. The morning sales at a small coffee house are normally distributed with a mean of $600 and a standard deviation of $60. What is the z-value for a $540 morning of sales?

1

0.8

1

0.8

1. Suppose that the lifetimes of light bulbs follows a normal distribution with mean 2000 hours and standard deviation of 200 hours. What is the probability that a randomly selected light bulb will last for more than 2100 hours?

0.3085

0.1915

0.6915

0.5000

1. Professor Difficult will only give an "A" grade to the students who score in the top 2.5% of an exam. If the scores follow a normal distribution with a mean of 70% and a standard deviation of 5%, what is the minimum grade that a student must score in order to receive an "A" grade?

72.5%

79.8%

80%

97.5%

1. A nation-wide survey of computer use at home indicated that the mean number of non-working hours per week spent on the internet is 11 hours with a standard deviation of 1.5 hours. If the number of hours is normally distributed what is the probability that a randomly selected person will have spent between 10 and 12 hours online over a one-week period?

0.5028

0.4908

0.5034

0.4972

1. A shoe store reviewed its purchases over the past year and discovered they were normally distributed with a mean of $110 and a standard deviation of $12. What is the probability that a randomly selected person will spend between $120 and $125 at the store?

0.2967

0.3944

0.6911

0.0977

1. The machinery in a cereal plant fills 350 g boxes of cereal. The specifications for the machinery permit for a certain amount of fill tolerance. It is found that the weights of filled cereal boxes are normally distributed with a mean of 350 g and a standard deviation of 4 g. What is the probability that a box of cereal is under filled by 5 g or more?

0.3944

0.1056

0.8944

0.6056

1. A nation-wide survey of computer use at home indicated that the mean number of non-working hours per week spent on the internet is 11 hours with a standard deviation of 1.5 hours. If the number of hours is normally distributed what is the probability that a randomly selected person will have spent in excess of 15 hours online over a one-week period?

0.9962

0.4962

0.5038

0.0038

1. A school will only accept students who score in the top 2% of an admissions test. If the scores follow a normal distribution with a mean of 70% and a standard deviation of 5%, what is the minimum grade that a student must score in order to be accepted?

72.5%

79.8%

80%

80.25%