There are 6 different letters and 6 correspondingly addressed envelopes. If the letters are randomly put in the envelopes, what is the probability that exactly 5 letters go into the correctly addressed envelopes?

Three different numbers are selected at random from the first 15 natural numbers. What is the probability that the product of two of the numbers is equal to third number?

If the letters of the word "TIRUPATI" are written down at random, then what is the probability that both Ts are always consecutive ?

In a bag, there are 8 red, 7 yellow and 6 green balls. If one ball is picked up at random, what is the probability that it is neither red nor green?

If four whole numbers are chosen randomly and multiplied, probability that last digit is 1,3,7 or 9?

A bag contains 5 black and 4 white balls. A man selects two balls at random. What is the probability that both of these are of the same colour?