Sales of a new line of athletic footwear are crucial to the success of a company. The company wishes to estimate the average weekly sales of the new footwear to within $200 with 95%
Reliability. The initial sales indicate that the standard deviation of the weekly sales figures is
Approximately $1400. How many weeks of data must be sampled for the company to get the
Information it desires?
A)14 weeks
B)97 weeks
C)189 weeks
D)37,648 weeks

Question

Quizplus · Accepted Answer

To find the sample size (n), use the formula for the sample size of a mean: n = (Z*σ/E)^2. Here, Z is the Z-score for 95% confidence (1.96), σ is the standard deviation ($1400), and E is the margin of error ($200). Plugging in these values gives n = (1.96*1400/200)^2 = 189 weeks.

Sales of a New Line of Athletic Footwear Are Crucial