Re: jnu 2012 doubts

Posted by Amit Goyal on May 05, 2013; 4:50pm
URL: http://discussion-forum.276.s1.nabble.com/jnu-2012-doubts-tp7580397p7580407.html

Only one of the following 3 statements regarding the no. of balls in an urn is true:
1)There are atleast 100 balls in the urn
2)There are less than 100 balls in the urn
3)There is at least one ball in the urn

Q. How many balls are there in the urn?
a)1
b)100
c)101
d)0

A. One way to do the above problem is do the following:
Given that only one of the three statements is true, you just check each option for how many of the statements are true assuming it to be correct.
If number of balls in urn is 1, then both statements 2) and 3) are correct. Thus option a) 1 is ruled out.
If number of balls in urn is 100, then both statements 1) and 3) are correct. Thus option b) 100 is ruled out.
If number of balls in urn is 101, then both statements 1) and 3) are correct. Thus option b) 101 is ruled out.
If number of balls in urn is 0, then only statement 2) is correct. Thus option d) 0 is the right answer.