Question

From a population sample of 50 CVS claims that they are 95% confident that their net monthly sales are between $30,000 to $31,500. A systematic sample of marginal sales is taken from 10 of their local stores with a standard deviation of 0.5 to determine if their net sales have reached marginal goals. The mean of the sample is $36,000. What determinations can be said about these chain stores?

Answer 1

Mean marginal sales = $36,000

The standard deviation of marginal sales = $0.5

95% Confidence Interval = $30,000 to $31,500

Sample size = 10

What determinations can be said about these chain stores?

95% Confidence Interval for the sample = Mean +- z*(Standard deviation/√Sample size)

= 36,000 +- 1.96*(0.5/√10)

= (35999, 36000.31)

Since the confidence interval for the 10 samples is larger than the confidence interval for the net monthly sales, we can say that these 10 stores have greater net monthly sales than the 50 CVS. Thus, we can say that their net sales have reached marginal goals.