Mattel Corporation produces a remote-controlled car that requires three AA batteries. The mean life of these batteries in this product is 35 hours with a standard deviation of 5.5 hours. As part of its testing program Sony tests samples of 16 batteries.
a. What proportion of the samples will have a useful life of more than 36 hours?
b. What proportion of the samples will have a useful life greater than 34.5 hours?
c. What proportion of the samples will have a useful life less than 33 hours?
d. What proportion of the samples will have a useful life between 32.5 hours and 37.0 hours?