Problem 38 Answer

Draw a 6 by 6 square. Plot the arrival time of one person vertically. Plot the arrival time of the other person horizontally. The times they arrive within 10 minutes of each other can be represented by a diagonal stripe across the square. The area of the entire square is 36. The area of the portions outside the stripe is 25. Thus the area of the stripe is 11. Considering the uniformity of the arrival times the probability of arriving within ten minutes is the area of the stripe divided by the area of the square = 11/36.

Michael Shackleford, A.S.A.