Source: Veritas Prep
Two hoses (A and B) are filling a pool. Working alone at their individual constant rates Hose A fill the pool in 6 hours, and Hose B could do it in 4 hours. If the two hoses work together until half the pool is full, and then Hose B finishes the pool alone, what fraction of the pool will have been filled by Hose B?
A. 1/2
B. 3/5
C. 3/4
D. 4/5
E. 7/8
The OA is D
Two hoses (A and B) are filling a pool. Working alone at
This topic has expert replies
-
- Moderator
- Posts: 2207
- Joined: Sun Oct 15, 2017 1:50 pm
- Followed by:6 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
GMAT/MBA Expert
- Jay@ManhattanReview
- GMAT Instructor
- Posts: 3008
- Joined: Mon Aug 22, 2016 6:19 am
- Location: Grand Central / New York
- Thanked: 470 times
- Followed by:34 members
Working together hoses A and B will fill 1/6 + 1/4 = 5/12 part of the poolBTGmoderatorLU wrote:Source: Veritas Prep
Two hoses (A and B) are filling a pool. Working alone at their individual constant rates Hose A fill the pool in 6 hours, and Hose B could do it in 4 hours. If the two hoses work together until half the pool is full, and then Hose B finishes the pool alone, what fraction of the pool will have been filled by Hose B?
A. 1/2
B. 3/5
C. 3/4
D. 4/5
E. 7/8
The OA is D
Thus, they together can fill completely in 12/5 hours
Given that they together filled half the pool, they would work for 1/2 of 12/5 = 6/5 hours
Part of the work done by hose B during that period = 1/4*6/5 = 3/10 part
Once half the pool is filled, only hose B fills the remaining half part; thus, part of the pool filled by hose B = 3/10 + 1/2 = 8/10 = 4/5
The correct answer: D
Hope this helps!
-Jay
_________________
Manhattan Review GMAT Prep
Locations: GMAT Classes Singapore | GMAT Tutoring Zurich | GRE Prep Hyderabad | TOEFL Prep Classes Manhattan | and many more...
Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
GMAT/MBA Expert
- Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7243
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
The combined rate of A and B is:BTGmoderatorLU wrote:Source: Veritas Prep
Two hoses (A and B) are filling a pool. Working alone at their individual constant rates Hose A fill the pool in 6 hours, and Hose B could do it in 4 hours. If the two hoses work together until half the pool is full, and then Hose B finishes the pool alone, what fraction of the pool will have been filled by Hose B?
A. 1/2
B. 3/5
C. 3/4
D. 4/5
E. 7/8
The OA is D
1/6 + 1/4 = 2/12 + 3/12 = 5/12
So the time it takes A and B to do half the pool is:
5/12 x t = 1/2
t = 1/2 x 12/5 = 12/10 = 6/5 hours
Hose A, whose rate is 1/6, has worked for 6/5 hours. Thus, hose A will have completed 1/6 x 6/5 = 1/5 of the pool. Since the rest of the pool will be completed by B, B will have completed 4/5 of the pool.
Answer: D
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews