Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 97)
97.
If x and y are positive integers such that (3x + 7y) is a multiple of 11, then which of the following will be divisible by 11 ?
4x + 6y
x + y + 4
9x + 4y
4x - 9y
Answer: Option
Explanation:

By hit and trial, we put x = 5 and y = 1 so that (3x + 7y) = (3 x 5 + 7 x 1) = 22, which is divisible by 11.

(4x + 6y) = ( 4 x 5 + 6 x 1) = 26, which is not divisible by 11;

(x + y + 4 ) = (5 + 1 + 4) = 10, which is not divisible by 11;

(9x + 4y) = (9 x 5 + 4 x 1) = 49, which is not divisible by 11;

(4x - 9y) = (4 x 5 - 9 x 1) = 11, which is divisible by 11.

Discussion:
23 comments Page 3 of 3.

Madhu said:   1 decade ago
Good Question Puneet, Can any body say answer for this?

Verkha said:   1 decade ago
Why x=5, y=1?

Puneet said:   1 decade ago
x=4 and y=3 gives 3x+7y= 12+21 = 33 divisible by 11.
From these values, x+y+4 = 4+3+4 = 11 again divisible by 11.


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