edited by
830 views
1 votes
1 votes
A student is to answer 10 out of 13 questions in an examination such that he must choose at least 4 from the first five questions. The number of choices available to him is
(A) 140
(B) 196

(C) 280

(D) 346
edited by

2 Answers

Best answer
2 votes
2 votes

There are two possibilities,

Case 1: 4 out of 5 starting questions are answered then 6 out of remaining 8 questions. Possible number of ways is 

5C× 8C= 140

Case 2: 5 out of 5 starting are answered and then 5 out of remaining 8. Possible number of ways is

5C× 8C= 56

So total number of ways is 140+56 = 196(option B)

selected by

Related questions

0 votes
0 votes
2 answers
1
sh!va asked Mar 10, 2017
863 views
An urn contains 5 black and 5 white balls. The probability of drawing two balls of the same coloura) 2/9b) 4/9c) 1/9d) 5/9
1 votes
1 votes
1 answer
2
sh!va asked Mar 10, 2017
3,843 views
Ten percent of screws produced in a certain factory turn out to be defective. Find the probability that in a sample of 10 screws chosen at random, exactly two will be def...
0 votes
0 votes
2 answers
3
sh!va asked Mar 10, 2017
696 views
If tan $\Theta$ = 8 / 15 and $\Theta$ is acute, then cosec $\Theta$(A) 8 / 17(B) 8 / 15(C) 17 / 8(D) 17 / 15
0 votes
0 votes
1 answer
4
sh!va asked Mar 10, 2017
488 views
If one root of the equation x 2+ px +12 =0 is 4, while the equation x 2 + px + q = 0 has equal roots, then the value of 'q' is(A) 49/4(B) 4 (C) 49/16(D) 12