Positive Integer y is 50 Percent of 50 Percent of Positive GMAT Problem Solving

Question: Positive integer y is 50 percent of 50 percent of positive integer x, and y percent of x equals 100. What is the value of x?

(A) 50
(B) 100
(C) 200
(D) 1,000
(E) 2,000

Correct Answer: C

Solution and Explanation:
Approach Solution 1:

y= 50x/100∗50/100
y= 25x/100 .......... (1)
xy/100= 100
y= 100∗100/x ..... (2)

Equating (1) & (2)

25x/100= 100∗100/x
25x^2= 100∗100∗100
x^2= 4∗100∗100
x= 2*10*10= 200

Approach Solution 2:

Given: x > 0 and y > 0.

"Positive integer y is 50 percent of 50 percent of positive integer x" --> y= 0.5∗(0.5x)= 0.25x;
"y percent of x equals 100" --> y/100∗x= 100 --> xy= 100∗100 --> substitute y --> x^2= 4∗100∗100 --> as
x > 0, only one solution
x= 200.

Approach Solution 3:

Positive integer y is 50 percent of 50 percent of positive integer x

We can write: y = (50/100)(50/100)(x)
Simplify: y = (1/2)(1/2)(x)
Simplify: y = x/4

y percent of x equals 100.
We can write: (y/100)(x) = 100
Simplify: xy/100 = 100
Multiply both sides of the equation by 100 to get: xy = 10,000

What is the value of x?
Take: xy = 10,000
Replace y with x/4 to get: x(x/4) = 10,000
Simplify: x²/4 = 10,000
Multiply both sides by 4 to get: x² = 40,000
Solve: x = 200 or x = -200
Since we're told x is positive, we can be certain that x= 200

“Positive integer y is 50 percent of 50 percent of positive”- is a topic of the GMAT Quantitative reasoning section of GMAT. This question has been taken from the book "The Official Guide for GMAT Review". To solve GMAT Problem Solving questions a student must have knowledge about a good amount of qualitative skills. GMAT Quant practice papers improve the mathematical knowledge of the candidates as it represents multiple sorts of quantitative problems.

Suggested GMAT Problem Solving Samples

Fees Structure

CategoryState
General15556

In case of any inaccuracy, Notify Us! 

Comments


No Comments To Show