A manufacturer of fuses claims that with 20% overload, the fuses will blow
in less than 10 minutes on the average. To test this claim, a random sample of 20 of
these fuses was subjected to a 20% overload, and the times it took them to blow had
the mean of 10.4 minutes and a sample standard deviation of 1.6 minutes. It can be
assumed that the data constitute a random sample from a normal population. Do they
tend to support or refute the manufacturer’s claim?
