Three hoses, x, y, and z, each pump water at a constant rate. How long

yes u are correct

Ans must be C

1) You have no information on Y, so insufficient
2) You have no information on Z, so insufficient

Combining 1 & 2 still insufficient because we do not know the constant rate of x or z

Each statement alone is insufficient. But in (I) its given that each of them ie x and z pumps at 120 gallons/hr. (II) says y pumps half the rate of x which is 60 gallons /hr. Isn't combining both sufficient to find how long it takes to fill the tank ?


Sent from my iPhone using GMAT Club Forum

I'm not sure about this one. The answer could be C if we can assume that all of the hoses started at the same time. But that is not explicitly stated. So, I think the answer is E.

R x T = W
X 120 g/hr
Y 60 g/hr
Z 120 g/hr

(120+120+60) x T = 30K this can be solved
or
120*t_x + 120*t_z + 60*t_y = 30K this can't be solved

We need to know the exact value of flow rate for x, y and z

St 1: flow rate of y not mentioned. INSUFFICIENT

ST 2: relation between x and y is given. but no exact value can be calculated. INSUFFICIENT

St 1 & St 2: y = x/2 and x = 120, z = 120. hence all three is known. SUFFICIENT

Option C

C should be the answer.
Combining both statements we will be able to find the answer.

OA plz ??

===========================
Hit +1 Kudos please, badly need them

It does not work this way. You should earn kudos by making quality posts and helping others.

Also, please post solutions along with one-letter answers. Thank you.

Option C

I: No information about pumping rate of hose Y: Insufficient

II: Pumping rate X = 2 * (Pumping rate Y)
No information on pumping rates. Insufficient

I + II: Pumping rate of all three hoses can be obtained. Assuming all three hoses pump for same duration of time (unless stated otherwise), the time required to fill tank of any volume can be estimated.

Hi All,

We're told that 3 pumps each pump water at a constant rate. We're asked how long it would take to fill up a 30,000 gallon tank.

If we're meant to assume that the tank starts off 'empty', then this is a relatively straight-forward prompt (we need the rates of the 3 pumps to answer the question).

1) Hoses X and Z each pump water at constant rate of 120 gallons per hour.

This Fact tells us nothing about the rate of Hose Y, so the answer will vary depending on that rate.
Fact 1 is INSUFFICIENT

2) Hose Y pumps water at half the rate of X.

This Fact tells us nothing about any of the rates, so the answer will vary depending on those rates.
Fact 2 is INSUFFICIENT

Combined, we know....
Hose X = 120 gallons/hour
Hose Z = 120 gallons/hour
Hose Y = 60 gallons/hour

We can now calculate how long it would take to pump 30,000 gallons of water. Again, if we're meant to assume that the tank starts off empty, then this information is SUFFICIENT. IF there's some water in the tank though, then the information is INSUFFICIENT (we would need to know the exact volume of water that needs to be pumped).

Final Answer:

GMAT assassins aren't born, they're made,
Rich