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 five 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 one second?

A)  64
B)  86
C)  100
D)  144
E)  169