Question

1. According to the Bureau labor of statistics, the mean weekly earnings for people working in a sales-related profession in 2010 was $660. Assume the weekly earnings are approximately normally distributed with a standard deviation of $75. If a salesperson was randomly selected, find the probability that his or her weekly earnings are at most $40.(choose the best answer)

a. .0004

b. .4246

c. .0478

d. .4182

e. .6255

2. A film distribution manager calculates that 8% of the films released are flops. If the manager is correct, what is the probability that the proportion of flops in a sample of 655 released films would differ from the population proportion by greater than 3%? round your answer to four decimal places.

3. A research scientist wants to know how many times per hour a certain strand of bacteria reproduces. The mean is found to be 13.6 reproductions and the population standard deviation is known to be 1.9. If a sample of 189 was used for the study, construct the 85% confidence interval for the true mean number of reproductions per hour for the bacteria. round answers to one decimal place.

Lower enpoint: Upper endpoint:

4. A manufacturer is developing a new type of paint. Test panels were exposed to various corrosive conditions to measure the protective ability of the paint. Based on the results of the test, the manufacturer has concluded that the mean life before corrosive failure for the new paint is 158 hours with a standard deviation of 30 hours. If the manufacturers conclusions are correct, find the probability that the paint on a sample of 64 test panels will have a mean life before corrosive failure of less than 145 hours. round your answer to four decimal places.

5. A random sample of 153 people was taken from a very large population. 75 of the people in the sample were females. The standard error of the proportion of females is (round your answer to 4 decimal places).

6. From a survey taken several years ago, the starting salaries of individuals with an undergraduate degree from business schools are normally distributed with a mean of $40,500 and a standard deviation of $4,500. What percentage of individual with an undergraduate business degree will likely have starting salaries of $35,325.00 to $45,675.00? (round you answer to 2 decimal places)

7. Sodas R Us just installed a new bottling machine. They ran the machine for 1 day and produced 150 bottles pulling off the line to sample. One key factor in the taste of the soda is the bubbly. The lab analyzed the following values for bubbly in the 5 bottles sampled.

2

3

8

14

2

What is the interval estimate of the bubbly that will provied a 95% confidence level that the mean bubbly of all the bottles of soda is within the interval estimate? (round answer to 3 decimal places)

lower limit: upper limit:

(answer as many as you can, thank you :))

Answer 1