S and T are two water pumps that run at constant rates. If pump T pump

Question

S and T are two water pumps that run at constant rates. If pump T pumped alone, how many more hours would it take for it to finish pumping a large container than it would take for pump S to accomplish the same task by itself?

(1) When both the water pumps work together, they finish pumping a large container in 2/3 rd the time it takes for pump S to finish the task alone.

(2) Pump T is capable of pumping a large container in twice the time that it takes pump S to accomplish the same task alone.

Kudos for a correct  solution .

chetan2u · Accepted Answer

immediate thinking on seeing this Q is ...
the answer asked is in terms of hour...
1) stat 1 gives us the ratio between S and T... insuff
2) stat 2 gives us the ratio between S and T again... insuff

combined nothing new.. E

reto · Answer

Not sure, but here what you can read out of the Statements:

1: Combined Time is 2/3x where x is the time of Pump S. > IS because there is no information about Pump T to S itself.
2: Pump T needs twice the time of Pump S. Alone it is insufficient.

Statement 1 + 2:
Combined Time 2/3X Hours
Pump S Time: X Hours
Pump T Time: 2X Hours

To solve, we needed to have at least X. Like this, there is no way to figure out the hours.

Answer E

GMATinsight · Answer

To answer this question, we need to know the relationship between the efficiencies of S and T and the actual amount of time taken by either of them or both of them together to fill the tank

Statement 1: When both the water pumps work together, they finish pumping a large container in 2/3 rd the time it takes for pump S to finish the task alone.

It gives us the relationship between the efficiencies of S and T but the value of time taken by any one of them or together (in hours) is unknown to arrive at any value of the number of hours

NOT SUFFICIENT

Statement 2: Pump T is capable of pumping a large container in twice the time that it takes pump S to accomplish the same task alone.

It gives us the relationship between the efficiencies of S and T but the value of time taken by any one of them or together (in hours) is unknown to arrive at any value of the number of hours

NOT SUFFICIENT

Combining the two statements

It gives us the relationship between the efficiencies of S and T but the value of time taken by any one of them or together (in hours) is unknown to arrive at any value of the number of hours

NOT SUFFICIENT

Answer: option E

IanStewart · Answer

It's a GMATPrep question with very slight changes to the wording: machines-x-and-y-work-at-their-respective-constant-rates-128011.html

lipsi18 · Answer

1. Time taken by s=S; T+S = 2/3 * S; but we do not know the value of time so insufficient
2. Time taken by t=2S,; we do not know how much time did S take to answer the question, so insufficient

C ) 1+2 still insufficient, as value of time is not mentioned. So Insufficient
Hence answer is E
Thanks,

Vaibhav21 · Answer

(1) When both the water pumps work together, they finish pumping a large container in 2/3 rd the time it takes for pump S to finish the task alone.

1/T+1/S=3/2S => 1/T=1/2S => 2S=T
Actual number of hours??
NS

(2) Pump T is capable of pumping a large container in twice the time that it takes pump S to accomplish the same task alone.
2S=T
Actual number of hours??
NS

Combining 
Actual number of hours??
NS

Answer E

ajdse22 · Answer

..my take on this-
The first statement -- when both pumps work together the time it takes to complete the entire task is 2/3 rd of what pump S will take.
let T be the time it takes pump T to finish the task alone and S be for pump S
stat#1 --> 1/T+1/S = 1/(2/3)S 
1/T + 1/S = 3/(2S). 
1/T = 3/(2S) - 1/S = 1/S*(1/2) = 1/2S => S/T = 1/2. Ratio between S and T cant be solved
stat #2--->Time it takes for T to do the job alone is twice the time it takes for S to do alone.
--> T/S = 2/1 --> this is identical to stat #1.
So we cant generate new info even after combining the statements. So E

manishtank1988 · Answer

My 2 cents: my 2 cents.png

Varthini · Answer

Both the statement doesn't cover the main point of the question the no. Of hours more than need by S alone... So option E.

Posted from my mobile device

summerbummer · Answer

---------------------------------------

I've used the following method, lemme know if this is logically correct:

For S: Rs
For T: Rt
Work: W

Ans will depend on: 1) rate of Rs & Rt

I. Rs+Rt=3W/2Ts

We get the value of Rt in terms of W & Ts (i.e. W/2Ts)

Not giving us a definite answer in terms of the number of hours, hence, NS

II. Ts = 2Ts

This as well isn't giving us a definite answer in terms of number of hours, hence, NS

Therefore, E.

Makes sense?

CEdward · Answer

The question is asking us to essentially figure out Tt and Ts, the amount of time that it takes the two pumps to do the job.

St1 - Tt+s = 2/3 x Ts 
The statement is saying that the amount of time that both pumps working together takes is 2/3 of the time that pump S takes alone. 
Insufficient b/c we don't know the time that it takes pump S to do it alone or the actual amount of time both pumps together take. Nor do we know how long it takes pump T to do it alone.

St2 - Tt = 2Ts
All we know is that the time that it takes pump T to do it alone is twice the time that it takes pump S. 
Insufficient.

Combined: Insufficient, we didn't get any closer to figuring out the time that it takes both objects to do it alone.

E is the answer.

bumpbot · Answer

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S and T are two water pumps that run at constant rates. If pump T pump

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S and T are two water pumps that run at constant rates. If pump T pump

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