If the probability of observing a car (read: at least one car) in 20 minutes on a highway is 609/625, what is the probability of observing a car (read: at least one) in 5 minutes (assuming constant default probability)?
The probability of seeing atleast one car in 20 minutes is 609/625
So the probability of seeing no cars in 20 minutes is 1  609/625 = 16/625
Assuming x to be the probability of seeing no cars in 5 minutes and with constant default probability, the changes of seeing no cars in 20 minutes are x^4.
So, x^4 = 16/625 or, x = 2/5
And the probability of seeing atleast one car in 5 minutes is 3/5

Posted by Rajat
on 20040409 15:37:15 