Statistics and Probability Answers

suppose you receive a shipment of ten televisions. Three of the televisions are defective. If two televisions are randomly selected, compute the probability that both televisions work. What is the probability at least one of the two televisions does not work?

A random sample of 205 college students was asked if they believed that places could be haunted and 65 of them responded "yes." Estimate the true proportion of college students who believe in the possibility of haunted places with 99% confidence. According to Time magazine, 37% of Americans believe that places can be haunted.

A quiz has twenty multiple choice questions, with five possible answers to each question. Alex has not studied for the quix and has no idea of the correct answers to each question.

A. what is the probability that he gets none of the questions correct?
B. What is the probability that he gets exactly 16 questions correct?
C.What would we expect his score to be out of 20?

A US Census American Housing Survey studies how US homeowners get to work, the survey consists of 1,000 homeowners and 1,000 renters. The result is:
Drivers to work Home Owners Renters Totals
Yes 824 681 1505
No 176 319 495
Total 1000 1000 2000
a) Given that the respondent drives to work, what is the probability that he or she is a home owners?
b) Given that the respondent is a homeowner, what is the probability that he or she drives to work?

Hypothesis testing: must state the null and the alternate hypotheses in WORD first, then go through the process of hypothesis testing.
Student also must state the findings (i.e., conclusion) in WORD.

You are the manger of a restaurant that delivers pizza to college dormitory rooms. You have just changed your delivery process in an effort to reduce mean time between the order and completion of delivery to 25 minutes, with a population standard deviation of 6 minutes.

A sample of 36 orders using the new delivery process yields a sample mean of 22.4 minutes.

At 0.05 level of significance, can you claim that the mean delivery time is 25 minutes?

Regression
Each of the following pairs represents the number of greeting cards sent and received by a group of friend:
Greeting cards sent Greeting cards received
13 6
9 10
7 14
5 12
1 18

(a) Construct a scatter plot.
(b) Determine the least square (i.e., regression) equation for these data
(c) Determine the standard error of the estimate
(d) If you send 20 greeting cards. How many greeting cards you expect to receive?

Assume that the equation for predicting the rate of inflation from the percent of unemployed workers is as follows: .90(X) + 11
If the unemployment rate equals 10 percent, the inflation rate should equal

If the standard deviation of a national accounting examination is 900, how large a sample is needed to estimate the true mean score within 5 points with 99% confidence?

A random sample of 50 four-year olds attending day care centers provided a yearly tuition average of $3,987 and the population standard deviation of $630. Find the 90% confidence interval of the true mean.

Procter & Gamble reported that an American family of four washes an average of 1 ton (2000 pounds) of clothes each year. If the population standard deviation of the distribution is 187.5 pounds, find the probability that the mean of a randomly selected sample of 50 families of four will be between 1980 and 1990 pounds.