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Q.

Jay has with him a total of Rs 29 in 5-rupee and 2-rupee denominators. The number of 5-rupee notes in one-half of one less than the number of 2-rupee notes. How many 5-rupee notes and 2-rupee notes does Jay have respectively?

 A.

7,3

 B.

3,7

 C.

2,5

 D.

5,2

 Hide Ans

Solution:
Option(B) is correct

Let $x$ be the 5-rupee notes and $y$ be the number of 2-rupee notes.

\(5x+2y=29\)-------- (i)

\(x=\dfrac{y-1}{2}\)

\(2x-y=-1\)-------- (ii)

On solving both the equation we get:

$x =\textbf{3}$ and $y =\textbf{7}$

Edit: For an alternative approach making use of the option choices, check comment by Sravan Reddy.


(3) Comment(s)


Sravan Reddy
 ()

Hi Abhijeet,

They said "Number of 5-rupee notes in one-half of one less than the number of 2-rupee notes"

So this condition is satisfied by only 2 options which are (3,7) and (2,5). So you can quickly check these two options: (3 Rs.5 notes & 7 Rs.2 notes make up 29 || 2 Rs.5 notes and 5 Rs.2 notes make up only 20)

So, answer is (3,7). This doesn't apply to all problems obviously but I am used to look for shortcuts in exam as soon as I see the question. If I don't find any, I do the actual solution. These methods really helped me in my CAT.

P.S. I understood that you did not understand many of my methods, but please do not use terms like "fake, out of world, messing, etc."



Sravan Reddy
 ()

Kill it in 10 sec:

=> Possible options: (3,7) and (2,5).

By calculating only 3,7 adds up to 29


ABHIJEET
 ()

either yur logic is fake or out of this world..are u just messing with our brains? if anyone can clear this logic by 21st century kindly reply here