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.

Nirmala said:   1 decade ago
Given conditions are
(1) x,y are positive integers and
(2) 3x+7y is multiple of 11.

So we can choose some integers
Lets take, x=2 & y=3 then 3*2+7*3=6+21=27,
27 is not multiple of 11,

These integers can also satisfy (2) condition.
Because we have to choose x=5,y=1 then 3*5+7*1=15+7=22,
22 is multiple of 11.

Like this only we have to choose.

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?


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