In: Statistics and Probability
A company manager thinks he is overpaying for fertilizer at $174 per ton. To find out, he collects fertilizer prices per ton from five distributors. Construct a 90% confidence interval from his results: 128, 140, 170, 166, and 156.
We have for given data,
Sample mean =152
Sample standard deviation =15.85
Sample size =5
Level of significance=1-0.90=0.1
Degree of freedom =4
t critical value is (by using t table)=
2.132
Confidence interval formula is
=(136.89,167.11)