4. The time required to assemble an electronic component is normally distributed with a mean of 12

minutes and a standard deviation of 1.5 min. Find the probability that the time required to assemble all

nine components (i.e. the total assembly time) is greater than 117 minutes.

(a) 2514

(b) .2486

(c) .4772

(d) .0228

(e) .0013