The Owner of Touchdown Sports Bar Wants to Develop a Time

Multiple Choice

The owner of Touchdown Sports Bar wants to develop a time standard for the task of mixing a specialty cocktail. In a preliminary study, he observed one of his bartenders perform this task seven times with an average of 90 seconds and a standard deviation of 5 seconds.
How many observations should be made if he wants to be 95.44 percent confident that the maximum error in the observed time is 1 second?

A) 64
B) 86
C) 100
D) 144
E) 169