8 6 A new design for the braking system on a certain type of

8 #6

A new design for the braking system on a certain type of car has been proposed. For the current system, the true average braking distance at 40 mph under specified conditions is known to be 120 ft. It is proposed that the new design be implemented only if sample data strongly indicates a reduction in true average braking distance for the new design.

Solution

For Z<-2.22, Z=0.0132 (from standard normal table)

For Z<-2.85, Z=0.0022 (from standard normal table)