7.5 Team Challenge (B)

A book publisher claims that its mean book length is 250 pages with a standard deviation of 70 pages. What is the probability that for a sample of 45 randomly selected books, the mean length of the book is less than 230 pages?

• 0.9719

• -1.91

• 0.2081

• 0.0281

A pencil manufacturer claims that its pencils have lengths that are normally distributed with a

mean of 6.0 inches and a standard deviation of 0.45 inches. What is the probability that a randomly chosen pencil will have a length more than 6.4 inches?

• 0.1867

• 0.8900

• 0.8133

• 0.1833

A local bottling company uses a filling machine to fill plastic bottles with Mr. Koch's favorite Diet Dr. Pepper. The bottles are supposed to contain 300 milliliters. In fact, the contents vary according to a normal distribution with a mean of 303 ml and a standard deviation of 3 ml. What is the probability that a random 12-pack of these bottles has a mean between 302 ml and 304 ml?

• 0.8749

• 0.7498

• 0.1251

• 1.15

The weights of the egg produced by a certain breed of hen are normally distributed with a mean of 65 grams and a standard deviation of 5 grams. If a random carton of a dozen eggs are selected at a nearby HyVee store, what is the probability the mean of this sample will be greater than 67 grams?

• 0.8023

• 0.9177

• 0.1977

• 0.0823