A camp director is interested in the mean number of letters each child sends during his or her camp session. The population standard deviation is known to be 2.5. Then the minimum sample needed if we...

Extracted text: A camp director is interested in the mean number of letters each child sends during his or her camp session. The population standard deviation is known to be 2.5. Then the minimum sample needed if we wish to be 93 °. confident that our estimate of mean is off by less than is: 11 O 21 15 O None of the other options