Question

People in the aerospace industry conducted a pilot study to determine the relationship between the weight and cost of a major object being sent into space. The results of the pilot study are contained in data file SP 13.53, contained in a folder under the CML Quizzes tab. Determine the number of observations needed to be 91% confident that the estimate of the average weight is within 0.25 units of the overall mean weight. Note: Assume that the pilot study standard deviation is a good estimate of the population standard deviation, that an appropriate value from the Z-table can be used, and that hand calculations are used to find the answer (i.e. do not use Kaddstat). Hint: in Excel, use Data > Data Analysis > Descriptive Statistics, to find the sample standard deviation.

Answer 1

Solution :

M.E = 15

C.L = 89%

z = 1.6

Margin of error for 89% confidence interval is given as:-

n = 45.027

n = 46

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