Question 180 Problem Solving 2018 GMAT Official Guide

Question 180 Problem Solving 2018 GMAT Official Guide

Video explanation: If $s>0$ and $\sqrt{\dfrac{r}{s}}=s$, what is r in terms of s…

Comments

Cathy Liangsays

What is the point of the problem stating s > 0? I took that into consideration and substituted s with an arbitrary number, 2, then solved. But you are actually supposed to just solve for r. The s > 0 statement is confusing.

The $s \gt 0$ condition is to make sure the square root is defined, the GMAT writers are just being precise and eliminating ambiguities. You can certainly solve this problem by selecting values for $s$. For example, if you set $s=2$, then plug in this value in to the original equation and then solve for $r$. In this case, you would obtain $r=8$, and then you would need to test the answer choices to find out the answer choice that matches with $r=8$.

Cathy Liang says

What is the point of the problem stating s > 0? I took that into consideration and substituted s with an arbitrary number, 2, then solved. But you are actually supposed to just solve for r. The s > 0 statement is confusing.

GMAT Quantum says

Hi Cathy,

The $s \gt 0$ condition is to make sure the square root is defined, the GMAT writers are just being precise and eliminating ambiguities. You can certainly solve this problem by selecting values for $s$. For example, if you set $s=2$, then plug in this value in to the original equation and then solve for $r$. In this case, you would obtain $r=8$, and then you would need to test the answer choices to find out the answer choice that matches with $r=8$.

Dabral