# MATH 221 Week 8 Final Exam2

**This file of MATH 221 Week 8 Final Exam2 gives answers on:**

1. The ages of 10 brides at their first marriage are given below.

a. Find the range of the data set.

b. Change 46.9 to 63.1 and find the range of the new data set.

c. Compare your answer to part (a) with your answer to part (b).

2. Find the indicated probability using the standard normal distribution.

3. A random sample of fifty-three 200-meters swims has a mean of 3.47 minutes and standard deviation of 0.06 minutes. Construct a 90% confidence interval for the population mean time. Interpret the results.

4. Write the null and alternative hypotheses. Indentify which is the claim. A study claims that the mean survival time for certain cancer patients treated immediately with chemotherapy and radiation is 16 points.

5. Assume the Poisson distribution applies. Use the given mean to find the indicated probability.

6. A soccer ball manufacturer wants to estimate the mean circumference of soccer balls within 0.05 in.

a. Determine the minimum sample size required to construct a 95% confidence interval for the population mean.

b. Repeat part (a) using a standard deviation of 0.30 in. which standard deviation requires a larger sample size?

7. For your study on the food consumption habits of teenage males, you randomly select 10 teenage males and ask each how many 12-ounce servings of soda he drinks each day. The results are listed below. At a=0.05, is there enough evidence to support the claim that the teenage males drink fewer than three 12-ounce servings of soda per day? Assume the population is normally distributed.

8. The times per week a student uses a lab computer are normally distributed, with a mean of 6.4 hours and a standard deviation of 1.1 hours. A student is randomly selected. Find the following probabilities.

a. Find the probability that the student uses a lab computer less than 5 hours per week.

b. Find the probability that the student uses a lab computer between 4 and 8 hours per week.

c. Find the probability that the student uses a lab computer more than 9 hours per week.

9. Ford wants to administer a satisfaction survey to its current customers. Using their customer database, the company randomly selects 90 customers and asks them about their level of satisfaction with the company. What type of sampling is used?

10. The graph to the right shows the number of cities with certain average annual rainfall amounts (in inches). Identify the level of measurements of the data listed on the horizontal axis in the graph.

11. Use technology to find the sample size, mean, median, medium data value, and maximum data value of the data. The data represents the amounts (in dollars) made by several families during a community yard sale.

12. A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 825 hours. A random sample of 44 light bulbs has a mean life of 806 hours with a standard deviation of 75 hours. Do you have enough evidence to reject the manufacturer's claim? Use a = 0.03

13. 31% of adults say cashews are their favorite kind of nut. You randomly select 12 adults and ask each to name his or her favorite nut. Find the probability that the number who say cashews are their favorite nut is (a) exactly three, (b) at least four, and (c) most two. If convenient , use technology to find the probabilities.