7.4 Team Challenge (B)

Compare the scores: a score of 75 on a test with a mean of 65 and a standard deviation of 8 and a score of 75 on a test with a mean of 70 and a standard deviation of 4.

• A score of 75 with a mean of 70 and a standard deviation of 4 is better.

• The two scores are statistically the same.

• You cannot determine which score is better from the given information.

• A score of 75 with a mean of 65 and a standard deviation of 8 is better.

An airline knows from experience that the distribution of the number of suitcases that get lost each week on a certain route is approximately normal with μ = 15.5 and σ = 3.6. What is the probability that during a given week the airline will lose between 10 and 20 suitcases?

• 0.1056

• 0.4040

• 0.3944

• 0.8341

The lengths of pregnancies of humans are normally distributed with a mean of 268 days and a standard deviation of 15 days. Find the probability of a pregnancy lasting less than 250 days.

• 0.0066

• 0.0606

• 0.1151

• 0.1591

The distribution of cholesterol levels in teenage boys is approximately normal with μ = 170 and σ = 30 (Source: U.S. National Center for Health Statistics). Levels above 200 warrant attention. Find the probability that a teenage boy has a cholesterol level greater than 225.

• 0.0606

• 0.0366

• 0.0012

• 0.0718