Question

The probability that traffic lights on a certain road will be green is 0.6. When a driver on that road approaches two traffic lights in a row, X is the number of traffic lights that are green. What is P(X=1)? Enter your answer, as a decimal, in the box. P(X=1) =

Answer 1

There are two possible ways for X=1: first light is green and second is red OR first light is red and second is green. The probabilities for these two options are to be summed: 0.6*0.4 + 0.4*0.6 to give the probability of exactly one light being green, namely 0.48.