You did everything right. The correct answer is 191
Hope this helps
P(<100) = P((new or change) & <100) = P(new & <100) + P(change & <100)
... = P(<100 | new)*P(new) + P(<100 | change)*P(change)
... = 0.90*0.70 + 0.20*0.30
... = 0.63 + 0.06 = 0.69 . . . . probability of completing a transaction in < 100 ms
What worksheet or are you talking to somebody else
