Question

A.) The amount of time customers spend waiting in line at a bank is normally distributed, with a mean of 3.5 minutes and a standard deviation of 0.75 minute. Find the probability that the time a customer spends waiting is as follows. (Round your answers to three decimal places.)

less than 4 minutes

less than 2 minutes

B.) The breaking point of a particular type of rope is normally distributed, with a mean of 310 pounds and a standard deviation of 24 pounds. What is the probability that a piece of this rope chosen at random will have the following breaking points? (Round your answers to three decimal places.)

less than 280 pounds

between 300 and 330 pounds

C.) The weights of all the boxes of corn flakes filled by a machine are normally distributed, with a mean weight of 13.5 ounces and a standard deviation of 0.4 ounce. What percent of the boxes will have the following weights? (Round your answers to one decimal place.)

weigh less than 13 ounces

weigh between 12.5 ounces and 14.5 ounces

D.) A manufacturer of light bulbs finds that one light bulb model has a mean life span of 1020 hr with a standard deviation of 81 hr. What percent of these light bulbs will last as follows? (Round your answers to one decimal place.)

at least 980 hr

between 800 and 880 hr

E.) Find the z-score, to the nearest hundredth, that satisfies the given condition.

0.348 square unit of the standard normal distribution is to the right of z.

F.) Find the z-score, to the nearest hundredth, that satisfies the given condition.

0.251 square unit of the standard normal distribution is to the left of z.

G.) Find the area, to the nearest thousandth, of the indicated region of the standard normal distribution.

The region where z < −0.88

H.) Find the area, to the nearest thousandth, of the standard normal distribution between the given z-scores.

z = 1.12 and z = 1.9

Answer 1

a)

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B)

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C)

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D)

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