GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Two pools in the shape of rectangular prisms are being fille
[#permalink]
07 Jan 2021, 10:03
07 Jan 2021, 10:03
Expert Reply
00:00
Question Stats:
76% (01:35) correct
23% (01:27) wrong based on 21 sessions
Hide Show timer Statistics
Two pools in the shape of rectangular prisms are being filled with water by pumps. The first pump fills its pool completely in one hour. The second pumps water twice as fast as the first pump, and fills a pool that is twice the width, twice the length, and the same depth of the first pool. How many hours does it take the second pump to fill its pool?
A. 1
B. 2
C. 4
D. 8
E. 16
Kudos for the right answer and explanation
A. 1
B. 2
C. 4
D. 8
E. 16
Kudos for the right answer and explanation
Re: Two pools in the shape of rectangular prisms are being fille
[#permalink]
08 Jan 2021, 07:59
08 Jan 2021, 07:59
2
Let's take Pump 1 and Pump 2
Rectangular prism shaped pool
Take length = l width = b depth = h
Volume of pool 1 = lbh
Pump 1 will take 1 hr to fill the water of volume \(lbh\)
Pool 2 has twice the length and twice the width and same depth
Volume of pool 2 = \((2*l)(2*b)(h)\) = \(4lbh\)
Pump 1 will take with it's speed to fill pool 2, 4 hours.
Now it is given that pump 2 fills twice the water than pump 1. So the speed will be half than the time taken by pump 2.
So Pump 2 will take 2 hours to fill Pool 2.
Answer B
Rectangular prism shaped pool
Take length = l width = b depth = h
Volume of pool 1 = lbh
Pump 1 will take 1 hr to fill the water of volume \(lbh\)
Pool 2 has twice the length and twice the width and same depth
Volume of pool 2 = \((2*l)(2*b)(h)\) = \(4lbh\)
Pump 1 will take with it's speed to fill pool 2, 4 hours.
Now it is given that pump 2 fills twice the water than pump 1. So the speed will be half than the time taken by pump 2.
So Pump 2 will take 2 hours to fill Pool 2.
Answer B
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Given Kudos: 172
Location: India
WE:Education (Education)
Re: Two pools in the shape of rectangular prisms are being fille
[#permalink]
03 Feb 2021, 00:18
03 Feb 2021, 00:18
1
For Pump 1:
W1 = Volume of the pool
T1 = 1 hour
R1 = Rate of filling the pool
So, T1 = W1/R1
For Pump 2:
W2 = 4W1 (twice the width and twice the length)
R2 = 2R1 (twice as fast)
So, T2 = W2/R2
T2 = 4W1/2R1 = 2W1/R1 = 2T1 (from above)
So, If pump 1 takes 1 hour then pump 2 will take 2 hours.
Hence, option B
W1 = Volume of the pool
T1 = 1 hour
R1 = Rate of filling the pool
So, T1 = W1/R1
For Pump 2:
W2 = 4W1 (twice the width and twice the length)
R2 = 2R1 (twice as fast)
So, T2 = W2/R2
T2 = 4W1/2R1 = 2W1/R1 = 2T1 (from above)
So, If pump 1 takes 1 hour then pump 2 will take 2 hours.
Hence, option B
