Question

(1 point) A market research firm supplies manufacturers with estimates of the retail sales of their products from samples of retail stores. Marketing managers are prone to look at the estimate and ignore sampling error. An SRS of 1414 stores this year shows mean sales of 8383 units of a small appliance, with a standard deviation of 7.67.6 units. During the same point in time last year, an SRS of 2424 stores had mean sales of75.62875.628 units, with standard deviation 14.614.6 units. An increase from 75.62875.628 to 8383 is a rise of about 9%.

1. Construct a 99% confidence interval estimate of the differenceμ1−μ2μ1−μ2, where μ1μ1 is the mean of this year's sales and μ2μ2 is the mean of last year's sales.

(a)   <(μ1−μ2)<<(μ1−μ2)<

(b) The margin of error is  .

2. At a  0.010.01 significance level, is there sufficient evidence to show that sales this year are different from last year?

A. No
B. Yes

Answer 1

1.

2.

ans-> A) No