A box contains n balls of which 2 are red and the rest are green. Two balls are to be selected at random one after the other from the box without replacement. If the probability of selecting 2 red balls is 1/28, find;
the value of n
the probability that a red is selected followed by a green
If the events are independent, the probability of both/all events occurring is determined by multiplying the probabilities of the individual events.
2/n * 1/(n-1) = 1/28
If they haven't been replaced, the probability of picking a red = 0.