# Hypothesis Testing of Mean: Self check out systems

Many grocery stores have installed self checkout systems. Below is the number of customers using the service for a sample of 15 days at the Wal-Mart in Boonton,

120 108 120 114 118 91 118 92 104 104 105 112 97 118 108 117

Is it reasonable to assume that the mean number of customers using self checkout is more than 100 per day? We use the .05 significance level.

The average $ value of all sales in the self checkout on these days were

1125 1452 1325 1055 1129 1165 1325 1275 1255 1422 1244 1351 1452 1444 1332 1111

Can we assume that the average sale on self checkout is less than 1250?

How would the answer to both questions change if both populations are known to be normally distributed with a standard deviation of 3 for the number of customers and 25 for the $ value of sales?

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#### Solution Summary

The solution provides step by step method for the calculation of testing of hypothesis. The solution also provides the change in answer when the population standard deviation is known. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.