Numbers 16, 17, 18, ..., 55 are written on separate slips (one number on one slip), kept in a bag and mixed well. One slip is chosen from the bag without looking into the bag. What is the probability that the number on the chosen slip is a prime number between 19 and 53?

A box contains 'x + 4' red, 'x – 1' green and 'x – 5' blue balls. If two balls are drawn from the bag one after another without replacement, then the probability of getting one red and one green ball is equal to the probability of getting a sum equal to or more than 8 when two fair dice are rolled. Find the probability of drawing a red ball when one ball is drawn at random from the bag.

Four persons are chosen at random from a group containing 3 men, 2 women, and 4 children. The probability that exactly two of them are children is: