M4maths Previous Puzzles

22 Mar 2010 Probability of meeting?

Ram and Rahim agree to meet at a place between 4 P.M. to 6 P.M. The first one to come waits for 24 minutes and then leaves. If the time of their arrival are independent and at random then what is the probability of a meeting between Ram and Rahim.

OPtion

1) 16/25
2) 1/25
3) 9/25
4) 1/5
5) 4/5
6) 3/5
7) 1/2
8) 2/3
9) 1/3
10)1/120

Solution

Total interval = 120 minutes
There are two persons hence total areal time interval = 120*120
Meeting interval = 24 minutes
Interval in which meeting is not possible = 96 minutes
There are two persons hence the total areal time interval for cancellation of meeting = 96*96
Total areal time interval for meeting = 120*120 � 96*96
Probability = (120*120 � 96*96)/ 120*120
= 9/25

Correct Option: 3 Best Solution (0)