If sr=t, what is the value of r?

Question

If  s\sqrt{r}=t , what is the value of r?

(1) r^2 = 625
(2) t/s = 5

nipunjain14 · Answer

Statement 1 : r = +/- 25 
Insufficient
Statement 2: s^2 *r = t^2
r = (t/s)^2
r = (5)^2
r = 25
Sufficient

Ans: B

abhimahna · Answer

Answer should be D.

Given,  s\sqrt{r}=t

Now we can infer from this equation that r cannot be -ve and \sqrt{r} = t/s

Now,

Statement 1 : r= 25 or -25. But we know that -25 is not a valid value. Hence, sufficient.

Statement 2 : t/s = 5 or \sqrt{r} = 5, hence r = 25. Sufficient.

Charvijain10 · Answer

Answer should be E.

1) r^2 = 625. So, r= (+/-)25
 But, we know that s√r=t. So, r has to be positive because otherwise √(-)r would be irrational. 
So, r= 25
SUFFICIENT

2)Now, squaring on both sides of s√r= t,
 s^2 r = t^2
 => r = t^2/s^2 = (t/s)^2
 => r = 5^2
 => r = 25
SUFFICIENT

So, D is the correct answer.

Posted from my mobile device

MV94 · Answer

Key consideration is the GMAT only deals with real numbers, therefore we cannot take the square root of a negative number. In the first stem, that excludes the negative outcome. As such, both stems are sufficient.

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If sr=t, what is the value of r?

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If sr=t, what is the value of r?

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