Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

You are not logged in.

## #1 Help Me ! » Stats help » 2006-01-06 05:57:30

NEKA
Replies: 1

Urban Plastic Products, Inc. is concerned about the inside diameter of the plastic PVC pipe it produces. A machine extrudes the pipe, which is then cut into 10-foot lengths. About 720 pipes are produced per machine during a two-hour period. How would you go about taking a sample from the two-hour production period?

A state meat inspector in Iowa has been given the assignment of estimating the mean net weight of packages of ground chuck labeled 3 pounds. Of course, he realizes that the weights cannot be precisely 3 pounds. A sample of 36 packages reveals the mean weight to be 3.01 pounds, with a standard deviation of 0.03 pounds.
a. What is the estimated population mean?
b. Determine a 95 percent confidence interval for the population mean.

The Human Relations Department of Electronics, Inc., would like to include a dental plan as part of the benefits package. The question is: How much does a typical employee and his or her family spend per year on dental expenses? A sample of 45 employees reveals the mean amount spent last year was \$1,820, with a standard deviation of \$660.
a. Construct a 95 percent confidence interval for the population mean.
b. The information from part (a) was given to the president of Electronics, Inc. He indicated he could afford \$1,700 of dental expenses per employee. Is it possible that the population mean could be \$1,700? Justify your answer.

Dole Pineapple, Inc. is concerned that the 16-ounce can of sliced pineapple is being overfilled. The quality-control department took a random sample of 50 cans and found that the arithmetic mean weight was 16.05 ounces, with a sample standard deviation of 0.03 ounces. At the 5 percent level of significance, can we conclude that the mean weight is greater than 16 ounces? Determine the p-value.

The owners of the Franklin Park Mall wished to study customer shopping habits. From earlier studies the owners are under the impression that a typical shopper spends 0.75 hours at the mall, with a standard deviation of 0.10 hours. Recently the mall owners added some specialty restaurants designed to keep shoppers in the mall longer. The consulting firm, Brunner and Swanson Marketing Enterprises, has been hired to evaluate the effects of the restaurants. A sample of 45 shoppers by Brunner and Swanson revealed that the mean time spent in the mall had increased to 0.80 hours.
a. Develop a test of hypothesis to determine if the mean time spent in the mall is more than
0.75 hours. Use the .05 significance level.
b. Suppose the mean shopping time actually increased from 0.75 hours to 0.77 hours. What is the probability this increase would not be detected?
c. When Brunner and Swanson reported the information in part (b) to the mall owners, the owners were upset with the statement that a survey could not detect a change from 0.75 to 0.77 hours of shopping time. How could this probability be reduced?

## #2 Re: Help Me ! » Another Stats question » 2006-01-02 13:06:42

I do not understand how you got these answers, cn you please explain?

## #3 Re: Help Me ! » Stats help » 2006-01-02 13:01:40

i need some help with this problem

## #4 Help Me ! » Stats help » 2006-01-02 13:00:24

NEKA
Replies: 1

An executive at Westinghouse drives from his home in the suburbs near
Pittsburgh to his office in the center of the city. The driving times
can be approximated by the normal distribution,with a mean of 35 minutes
and a standard deviation of 8 minutes.

a.What percent of the days will it take him 30 minutes or less to drive
to work?

b.What percent of the days will it take him 40 minutes or more to drive
to work?

c.Explain to the executive why the probability is nearly 0 that it will
take him exactly 40 minutes to get to work.

d.The executive did not understand your answer to part c. How would you
estimate the percent of days it takes 40 minutes to drive to
work?(Hint:Within what range of values would the times be rounded to
40?)

## #5 Help Me ! » Last problem in Stats » 2006-01-02 07:50:39

NEKA
Replies: 1

An executive at Westinghouse drives from his home in the suburbs near
Pittsburgh to his office in the center of the city. The driving times
can be approximated by the normal distribution,with a mean of 35 minutes
and a standard deviation of 8 minutes.

a.What percent of the days will it take him 30 minutes or less to drive
to work?

b.What percent of the days will it take him 40 minutes or more to drive
to work?

c.Explain to the executive why the probability is nearly 0 that it will
take him exactly 40 minutes to get to work.

d.The executive did not understand your answer to part c. How would you
estimate the percent of days it takes 40 minutes to drive to
work?(Hint:Within what range of values would the times be rounded to
40?)

## #6 Help Me ! » Another Stats question » 2006-01-02 07:01:55

NEKA
Replies: 2

To reduce theft, the Meredeth Company screens all its employees with a
lie detector test that is known to be correct 90 percent of the time
(for both guilty and innocent subjects). George Meredeth decides to fire
all employees who fail the test. Suppose 5 percent of the employees are
guilty of theft.

a. What proportion of the workers are fired?

b. Of the workers fired, what proportion are actually guilty?

c. Of the workers not fired, what proportion are guilty?

d. What do you think of George's policy?

## #7 Re: Help Me ! » Statistics help ASAP, Please » 2006-01-02 05:41:09

Hi i am new in this forum and i am having some probelms with statistics. Can anyone please help?

## #8 Help Me ! » Statistics help ASAP, Please » 2006-01-02 05:35:08

NEKA
Replies: 2

The Department of Commerce,Bureau of the Census,reported the following
information on the number of wage earners in more than 56 million
American homes.

Number of Earners     Number (in thousands)

0                                      7,083

1                                     18,621

2                                      22,414

3                                       5,533

4 or more                           2,797

a.What is the median number of wage earners per home?

b.What is the modal number of wage earners per home?

c.Explain why you cannot compute the mean number of wage earners per
home.
Hint - the data above is an example of grouped data.