Q1.

Let Z be a standard normal random variable. Use the calculator provided, to determine the value of c.

=P??c?Zc0.9451

Carry your intermediate computations to at least four decimal places. Round your answer to two decimal places.

Q2.

A psychologist has designed a questionnaire to measure individuals' aggressiveness. Suppose that the scores on the questionnaire are normally distributed with a standard deviation of 90. Suppose also that exactly 15% of the scores exceed 800. Find the mean of the distribution of scores. Carry your intermediate computations to at least four decimal places. Round your answer to at least one decimal place.

Q3.

According to a recent survey, the salaries of entry-level positions at a local company have a mean of $41,750

and a standard deviation of $7000. Assuming that the salaries of these entry-level positions are normally distributed, find the proportion of employees in entry-level positions at the company who earn at least $53,000. Round your answer to at least four decimal places.

Q4.

Alcohol withdrawal occurs when a person who uses alcohol excessively suddenly stops the alcohol use. Studies have shown that the onset of withdrawal is experienced a mean of 39.5 hours after the last drink, with a standard deviation of 19 hours. A sample of 35 people who use alcohol excessively is to be taken. What is the probability that the sample mean time between the last drink and the onset of withdrawal will be 42 hours or more?

Carry your intermediate computations to at least four decimal places. Round your answer to at least three decimal places.

Q5.

Below are four bivariate data sets and their scatter plots. (Note that all of the scatter plots are displayed with the same scale.) Each data set is made up of sample values drawn from a population.

x y n V 11 - 1.0 8.2 X 10- 1.0 7.9 10- X 9_ 2.0 5.2 X X 2.0 7.2 9 - 8 - 8- X X 3.0 10.4 3.0 7.8 X X X 4.0 5.9 X 4.0 6.0 X X 5.0 1.9 X 5.0 6.9 X X X 6.0 4.9 X X 6.0 4.6 X 7.0 9.0 X 7.0 4.9 8.0 3.5 8.0 3.6 9.0 9.6 9.0 4.6 10.0 6.7 Figure 1 10.0 2.5 Figure 2 W t 11- m n In 1.0 3.7 10- 1.0 10.0 10 - X 2.0 5.9 9- X X 2.0 9.0 X 8- X 3.0 7.5 X X X 3.0 8.0 X 4.0 4.6 6- X 4.0 7.0 X 5 _ X 5.0 5.0 X X 5.0 6.0 X X X 6.0 8.4 3- 6.0 5.0 X 7.0 5.1 7.0 4.0 X 8.0 7.1 8.0 3.0 X o 9.0 9.2 9.0 2.0 10.0 7.4 Figure 3 10.0 1.0 Figure 4A laboratory in New Mexico is interested in finding the mean chloride level for a healthy resident in the state. A random sample of 100 healthy residents has a mEq mEq mean chloride level of 104 T. If it is known that the chloride levels in healthy individuals residing in New Mexico have a standard deviation of 38 , find a 90% confidence interval for the true mean chloride level of all healthy New Mexico residents. Then give its lower limit and upper limit. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. (If necessary, consult a list of formulas.) Lower limit: D Upper limit: U Use the ALEKS calculator to solve the following problems. (a) Consider a t distribution with 24 degrees of freedom. Compute P( 1.17