# Permutations and Combinations Questions - Permutation and Combinations

26:

How many 10 digits numbers can be written by using the digits 1 and 2 ?

 A. 10C1 + 9C2 B. 210 C. 10C2 D. 10! Answer Report Discuss Option: B Explanation : Click on Discuss to view users comments. Write your comments here:
27:

In an examination there are three multiple choice questions and each question has 4 choices. Number of ways in which a student can fail to get all answers correct is

 A. 11 B. 12 C. 27 D. 63 Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. Write your comments here:
28:

The number n of ways that an organization consisting of twenty -six members can elect a president, treasurer, and secretary (assuming no person is elected to more than one position) is

 A. 15600 B. 15400 C. 15200 D. 15000 Answer Report Discuss Option: A Explanation : The president can be elected  in twenty-six different ways; following this, the treasurer can be elected in twenty five different ways since the person chosen president is not elegible to be treasurer); and following this, the secretary can be elected in twenty-four different ways. Thus, by above principle of counting, there are n =26 x 25 x 24 =15600 different ways in which the organization can elect the officers. Click on Discuss to view users comments. Write your comments here:
29:

Ten different letters of an alphabet are given. Words with five letters are formed from these given letters. Then the number of words which have at least one letter repeated is

 A. 69760 B. 30240 C. 99748 D. none of these Answer Report Discuss Option: A Explanation : Click on Discuss to view users comments. Write your comments here:
30:

There are (n + 1) white and (n + 1) black balls each set numbered 1 to n + 1. The number of ways in which the balls can be arranged in a row so that adjacent balls are of different colours, is

 A. (2n + 2)! B. (2n + 2)! X 2 C. (n + I)! x 2 D. 2 {(n + 1)!}2 Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. Write your comments here:

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