Dr tanveer Kifayat

Q. No.1: A bag contains 3 white, 1 black and 3 red ball. Two balls are drawn from the well shaked bag. Find the probability of both the balls being black and its mean. Q. No.2: Telephone calls are being placed through a certain exchange at random times o average of four per minute. Assuming a Poisson process, determine the probability that in a 15-second intervals, there are 3 or more calls