The median of a random variable X is the real number m such that P(X ≤ m) = 1/2. This term is used in Exercises 52 through 55.

Find the median time you have to wait for the light to turn green in Example 6.4.3.

Data from Example 6.4.3.

A certain traffic light remains red for 40 seconds at a time. Lila arrives (at random) at the light and finds it red. Use an appropriate uniform density function to find the probability that she will have to wait at least 15 seconds for the light to turn green.