Bag A contains 3 white and 2 red balls. Bag B contains only 1 white ball. A fair coin is tossed. If head appears then 1 ball is drawn at random from bag A and put into bag B. However if tail appears then 2 balls are drawn at random from bag A and put into bag B. Now one ball is drawn at random from bag B. Given that the drawn ball from B is white, the probability that head appeared on the coin is
Let $$X$$ and $$Y$$ be the set of all positive divisors of 400 and 1000 respectively (including 1 and the number). Then $$n(X \cap Y)$$ is equal to
In a 12 storey house, 10 people enter a lift cabin. It is known that they will leave the lift in pre-decided groups of 2, 3 & 5 people at different storeys. The number of ways they can do so if the lift does not stop up to the second storey is
If three numbers $$a, b, c$$ constitute both an A.P and G.P, then