A class consists of 80 students, 25 of them are girls and 55 are boys. If 10 of them are rich and the remaining are poor and also 20 of them are intelligent, then the probability of selecting an intelligent rich girls is a.`5//128` b. `25//128` c. `5//512` d. none of these

Two players toss 4 coins each. The probability that they both obtain the same number of heads is a. 5//256 b. 1//16 c. 35//128 d. none of these

A cricket club has 15 members, of them of whom only 5 can bowl. If the names of 15 members are put into a box and 11 are drawn at random, then the probability of getting an eleven containing at least 3 bowlers is a. 7//13 b. 6//13 c. 11//158 d. 12//13

If odds against solving a question by three students are 2:1, 5:2, and 5:3, respectively, then probability that the question is solved only by one student is a. 31//56 b. 24//56 c. 25//56 d. none of these

Five different marbles are placed in 5 different boxes randomly. Then the probability that exactly two boxes remain empty is (each box can hold any number of marbles) 2//5 b. 12//25 c. 3//5 d. none of these

A bag contains some white and some black balls, all combinations of balls being equally likely. The total number of balls in the bag is 10. If there ball are drawn at random without replacement and all of them are found to be black, the probability that eh bag contains 1 white and 9 black balls is a. 14//55 b. 12//55 c. 2//11 d. 8//55

A fair die is thrown 20 times. The probability that on the 10th throw, the fourth six appears is a. "^20 C_(10)xx5^6//6^(20) b. 120xx5^7//6^(10) c. 84xx5^6//6^(10) d. none of these

Five horses are in a race. Mr. A selects two of the horses at random and bets on them. The probability that Mr. A selected the winning horse is (A) 3/5 (B) 1/5 (C) 2/5 (D) 4/5

A dice is thrown six times, it being known that each time a different digit is shown. The probability that a sum of 12 will b e obtained in the first three throws is 5//24 b. 25//216 c. 3//20 d. 1//12

To fill 12 vacancies there are 25 candidates of which 5 are from scheduled caste. If three of the vacancies are reserved for scheduled caste candidates while the rest are open to all; the number of ways in which the selection can be made is a. 5C_3xx^(22)C_9 b. 22 C_9-^5C_3 c. 22 C_3+^5C_3 d. none of these