One of 10 keys open the door. If we try the keys one after another, then find the following: (i) The probability that the door is opened on the first attempt. (ii) The probability that the door is opened on the second attempt. (iii) The probability that the door is opened on the 10th attempt.

One of the ten available keys opens the door. If we try the keys one after another, then find the following (i) the probability that the door is opened in the first attemt. (ii) the probability tht the door is opened in the second attempt. (iii) the probability that the door is opened in the third attempt. (iv) the probability that the door is opened in the tenth attempt.

A box contains 10 tickets numbered from 1 to 10 . Two tickets are drawn one by one without replacement. The probability that the "difference between the first drawn ticket number and the second is not less than 4" is

A bag contains 6 red and 4 balls. Two balls are drawn at random one after the other.Find the probability that both the drawn balls are white, when (i) the first drawn ball is not replaced before the second drawing, (ii) the first drawn ball is replaced before the second drawing.

Two balanced dice are thrown together. Write down the sample space. Now find the probability of obtaining (i) 4 in both the dice (ii) doublets and (iii) 2 in one and 5 in the other.

Consider a game played by 10 people in which each flips a fair up coin at the same time. If all but one of the coins comes up the same, then the odd persons wins (e.g., if there are nine tails and one head then head wins). If such a situation does not occur, the players flips again. Find the probability that game is settled on or after nth toss.

In a class of 60 students. 30 opted for NCC, 32 opted for NSS and 24 opted for both NCC and NSS. If one of these students is selected at random, find the probability that (i) The student opted for NCC or NSS. (ii) The student has opted neither NCC nor NSS. (iii) The students has opted NSS but not NCC.

A person entering an empty room suddenly finds a snake right in front on opening the door. Which one of the following is likely to happen in his neuro-hormonal control system

Out of 20 games of chess played between two players A and B, A won 12, B won 4 and 4 ended in a tie. In a tournament of three games find the probability that (i) B wins all three (ii) B wins at least one (iii) two games end in a tie.