Chapter 11.8, Problem 4WE

(a)

To determine

To Find: The probability there will be train waiting.

Answer to Problem 4WE

  $\frac{1}{7}$

Explanation of Solution

Given: At a subway stops, a train arrives at every six minutes, waits one minute and then leaves. If you arrive random.

Waiting time of train is one minute.

Time for arrival next train is six minutes.

i.e.

Total time = $1+6=7\min$

Thus

The probability for finding a train waiting.

  $P=\frac{1}{7}$

(b)

To determine

To Find: The probability that you will wait no more than two minutes before one arrives.

Answer to Problem 4WE

  $\frac{2}{5}$

Explanation of Solution

Given: If you arrive and there is not train waiting.

Total minutes = $6$

The train is waiting for one minute.

Now total time is $6-1=5$

The probability for wait no more than two minutes.

  $P=\frac{2}{5}$