Final answer:
The estimated margin of error is 15.4 and the sample mean is 64.4.
Step-by-step explanation:
To find the estimated margin of error, we look at the confidence interval provided by the store manager. The confidence interval given is (49.0, 79.8), so the estimated margin of error can be calculated as the half of the difference between the upper and lower bounds of the confidence interval. Therefore, the estimated margin of error is (79.8 - 49.0) / 2 = 15.4.
To find the sample mean, we take the average of the upper and lower bounds of the confidence interval. So, the sample mean is (49.0 + 79.8) / 2 = 64.4.