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Confidence interval pooled t-test

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Wize University Statistics Textbook > Inference for Two Population Means

Confidence Interval Pooled t

3 Activities

Zelda runs coffee shops in Burnaby. She wants to compare the sales in her Metrotown location and the sales in her Brentwood Mall location. Days are randomly sampled. Summary:

Sample SizeMean Sales ($)Standard DeviationMetrotown61$460159Brentwood Mall61$33592\begin{array}{|c|c|c|c|}\hline &\text{Sample Size} & \text{Mean Sales (\$)} & \text{Standard Deviation}\\\hline \text{Metrotown} & 61 &\$460& 159\\\hline \text{Brentwood Mall}& 61& \$335 & 92\\\hline \end{array}

Construct a 90% confidence interval for the difference in the true mean sales. Assume equal population variances.

Is there evidence that the average sales differ between the two coffee shops?
More Confidence Interval Pooled t Questions:
Confidence interval and Hypothesis testing
Mr. Emin loves going to Starbucks drive-thru on his busy mornings but he can’t help feeling frustrated by the amount of time he has to wait to be served. He decides to go to Starbucks for 5 days and Tim Hortons for 7 days. He records the length of time, rounded to the nearest minute he has to wait each day to be served. Here is the data
The standard deviation for Starbucks waiting time is 3.082.
The standard deviation for Tim Hortons waiting time is 2.160.