Thetis Mfg. says that its outboard watercraft engine's noise level at 75 percent throttle averages 100 decibels or less from the operator's seating position. A random sample of 8 noise level measurements showed a mean of 106 decibels with a standard deviation of 7.2 decibels. At the 5 percent level of significance, should we reject Thetis's claim?