Posted: September 14th, 2017

Homework

Business Statistics II – STAT222

Summer 2015

(Due on 12/8/2015)

Name: 1-___________________________________________ Student ID ________________

2-___________________________________________ Student ID ________________

3-___________________________________________ Student ID ________________

4-___________________________________________ Student ID ________________

Instructions

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This homework is a group homework (group of 4 students maximum)

It counts for 5% of your total grade.

Show All the Steps

Question One: Read the Problem [2 points]

A real estate agent believes that home with swimming pools take longer to sell than home without

swimming pools. A random sample of each type of recently sold homes was taken where the number of

days on the market is recorded. Results are:

Sample mean

Sample Standard deviation

Sample size

Homes with pool

77 days

8.4 days

19

Homes without pool

65 days

7.2 days

23

Assuming that the populations are normally distributed:

a. [1 point] What assumption we can make about the population variances: equal or unequal?

Interpret your results?

b. [1 point] Conduct the appropriate hypothesis test to determine if the real estate agent is correct. Use

the 0.05 level of significance.

Question Two: Read the Problem [2 points]

A maker of toothpaste is interested in testing whether the proportion of adults (over age 18) who use its

toothpaste and have no cavities within a six-month period is any different from the proportion of children

(18 and under) who use the toothpaste and have no cavities within a six-month period. To test this, it has

selected a sample of adults and a sample of children randomly from the population of those customers who

use their toothpaste. The following results were observed.

Sample size

Number with 0 cavities

Adults

100

83

Children

200

165

a. [1 point] Based on these sample data and using a significance level of 0.05, what conclusion should

be reached? What is the p-value.

b.

[1 point] Develop and interpret the desired 95 percent confidence interval estimate.

Question Three: Read the Problem [1 points]

Random samples from two normal populations produced the following statistics:

?? = 10

?? =10

?? = 28

?? =19

a. [1 point] Estimate with 95% confidence the ratio of the two population variances.

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