# Question

Because of the high cost of energy, home-owners in northern climates need to find ways to cut their heating costs. A building contractor wanted to investigate the effect on heating costs of increasing the insulation. As an experiment, he located a large sub-development built around 1970 with minimal insulation. His plan was to insulate some of the houses and compare the heating costs in the insulated homes with those that remained un-insulated.

However, it was clear to him that the size of the house was a critical factor in determining heating costs. Consequently, he found 16 pairs of identical sized houses ranging from about 1,200 to 2,800 square feet. He insulated one house in each pair (levels of R20 in the walls and R32 in the attic) and left the other house unchanged. The heating cost for the following winter season was recorded for each house.

a. Do these data allow the contractor to infer at the 10% significance level that the heating cost for insulated houses is less than that for the un-insulated houses?

b. Estimate with 95% confidence the mean savings due to insulating the house.

c. What is the required condition for the use of the techniques in parts (a) and (b)?

However, it was clear to him that the size of the house was a critical factor in determining heating costs. Consequently, he found 16 pairs of identical sized houses ranging from about 1,200 to 2,800 square feet. He insulated one house in each pair (levels of R20 in the walls and R32 in the attic) and left the other house unchanged. The heating cost for the following winter season was recorded for each house.

a. Do these data allow the contractor to infer at the 10% significance level that the heating cost for insulated houses is less than that for the un-insulated houses?

b. Estimate with 95% confidence the mean savings due to insulating the house.

c. What is the required condition for the use of the techniques in parts (a) and (b)?

## Answer to relevant Questions

The cost of health care is rising faster than most other items. To learn more about the problem a survey was undertaken to determine whether differences in health care expenditures exist between men and women. The survey ...Refer to Examples 13.4 and 13.5. Suppose that another experiment is conducted. Finance and marketing MBA majors were matched according to their undergraduate GPA. As in the previous examples, the highest starting salary ...Random samples from two normal populations produced the following statistics:a. Estimate with 95% confidence the ratio of the two population variances.b. Repeat part (a) changing the sample sizes to n1 = 25 and n2 = 25.c. ...Random samples from two binomial populations yielded the following statistics:p̂1 = .45 n1 = 100 p̂2 = .40 n2 = 100a. Calculate the p-value of a test to determine whether we can infer that the population ...Plavix is a drug that is given to angioplasty patients to help prevent blood clots. A researcher at McMaster University organized a study that involved 12,562 patients in 482 hospitals in 28 countries. All the patients had ...Post your question

0