Discrete Random Variables – Mean — Unit test Answers

The daily high temperatures in a vacation resort city are approximately Normal, with a mean temperature of 75 degrees Fahrenheit and a standard deviation of 6 degrees. If a weather forecast predicts the high temperature will be at most 68 degrees, the city provides fewer lifeguards for the city beaches. On what percentage of days will fewer lifeguards be provided?Find the z-table here.

The graph shows the distribution of the amount of time (in minutes) people spend watching TV shows on a popular streaming site. The distribution is approximately Normal, with a mean of 71 minutes and a standard deviation of 15 minutes.

The graph shows the distribution of the amount of time (in minutes) people spend watching TV shows on a popular streaming service. The distribution is approximately Normal, with a mean of 71 minutes and a standard deviation of 15 minutes.

The diameters of cherry tomatoes produced by a large farm have an approximately Normal distribution, with a mean diameter of 22 mm and a standard deviation of 2.5 mm. After they are picked and washed, tomatoes with a diameter of at most 15 mm or at least 30 mm are rejected and not sold. What proportion of such tomatoes are rejected?Find the z-table here.

In a standard Normal distribution, what proportion of observations lie between z = 0.15 and z = 1.20?Find the z-table here.

Keeping car tires inflated is essential to safe driving. For one type of car tire, the tire pressure in pounds per square inch (psi) is assumed to be approximately Normal, with a mean of 35 psi and a standard deviation of 2 psi. What percentage of tires are inflated to a pressure between 33.5 and 36 psi?Find the z-table here.

The graph shows the distribution of weights (in pounds) for male duck-billed platypuses.

The graph shows the distribution of the amount of time (in minutes) people spend watching TV shows on a popular streaming service. The distribution is approximately Normal, with a mean of 71 minutes and a standard deviation of 15 minutes.