If s/t = 2, then the value of which of the following can be determined

Question

If s/t = 2, then the value of which of the following can be determined?

I. 2t/s
II. (s - t)/t
III. (t - 1)/(s - 1)

A. I only
B. III only
C. I and II only
D. II and III only
E. I, II, and III

PS77602.01

Archit3110 · Answer

given 
s=2t
so 
I. 2t/s = solve we get 1 
II. (s - t)/t = solve we get 1 
III. (s - 1)/(t - 1) = no value
IMO C

KSBGC · Answer

s/ t = 2 /1 .......we can use ratio. ...........only i and ii are correct .

BrentGMATPrepNow · Answer

I. 2t/s  
If s/t = 2, then t/s = 1/2
So, 2t/s = 2(t/s) = (2)(1/2) = 1
So we CAN determine the value of 2t/s

II. (s - t)/t  
Here, we can use a nice fraction property that says:   (a - b)/c = a/c - b/c  
We get: (s - t)/t = s/t - t/t = s/t - 1 = 2 - 1 = 1
So we CAN determine the value of (s - t)/t

III. (s - 1)/(t - 1)  
Notice that, if s/t = 2, it COULD be the case that s = 2 and t = 1
When we plug these values into the expression we get: (s - 1)/(t - 1) = (2 - 1)/(1 - 1) = 1/0, which is undefined. 
So we CANNOT determine the value of (s - 1)/(t - 1)

Answer: C

Cheers, 
Brent

ScottTargetTestPrep · Answer

Since s = 2t, we can substitute 2t for s in each expression:

I. 2t / 2t = 1

I is correct.

II. (2t - t) / t = 1

II is correct.

III. (2t -1) / (t - 1)

We see that different values of t will yield a different value of the expression, so III is not correct.

Answer: C

siddharthaggarwal · Answer

Bunuel  in GMAT official advanced, III. t-1/s-1 not s-1/t-1

Posted from my mobile device

Bunuel · Answer

_____________________
Edited. Thank you.

Kimberly77 · Answer

BrentGMATPrepNow , For I & II, are below calculations correct too?
I, s=2t
 0=2t/s

II, s=2t
 s-t=2t-t
 s-t = t
 s-t/t = 0

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If s/t = 2, then the value of which of the following can be determined

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If s/t = 2, then the value of which of the following can be determined

Prep Toolkit

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