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Retired Moderator
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WE:Education (Education)
A plumber is twice efficient than his apprentice. After the plumber
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28 Mar 2021, 22:42
28 Mar 2021, 22:42
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Question Stats:
67% (01:59) correct
32% (02:19) wrong based on 192 sessions
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A plumber is twice efficient than his apprentice. After the plumber has worked alone for \(2\) hours, his apprentice joins him and working together they complete the job \(3\) hours later.
A. The quantity in Column A is greater
B. The quantity in Column B is greater
C. The two quantities are equal
D. The relationship cannot be determined from the information given
Quantity A |
Quantity B |
Number of hours required for apprentice alone to finish the job |
10 |
A. The quantity in Column A is greater
B. The quantity in Column B is greater
C. The two quantities are equal
D. The relationship cannot be determined from the information given
Re: A plumber is twice efficient than his apprentice. After the plumber
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30 Mar 2021, 01:08
30 Mar 2021, 01:08
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If rate at which plumber works is 2x, rate at which apprentice works is x.
Working together at x+2x = 3x rate for 3 hours, they finished 3*3x = 9x work together. Working alone, apprentice will finish 9x work in 9x÷x = 9 hours.
Also, if plumber does a job in 2 hours, the apprentice is definitely going to take 4 hours, given the plumber is twice as efficient.
Therefore, the apprentice alone will take 9+4 = 13 hours. Hence, A is the correct answer.
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Working together at x+2x = 3x rate for 3 hours, they finished 3*3x = 9x work together. Working alone, apprentice will finish 9x work in 9x÷x = 9 hours.
Also, if plumber does a job in 2 hours, the apprentice is definitely going to take 4 hours, given the plumber is twice as efficient.
Therefore, the apprentice alone will take 9+4 = 13 hours. Hence, A is the correct answer.
Posted from my mobile device
General Discussion
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Given Kudos: 172
Location: India
WE:Education (Education)
Re: A plumber is twice efficient than his apprentice. After the plumber
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30 Mar 2021, 02:40
30 Mar 2021, 02:40
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Explanation:
More efficient means less time or more work!
Let us assume it takes the plumber alone \(x\) hours to finish the job
So his apprentice would require \(2x\) hours to finish the same job
Work done by Plumber + Work done by the apprentice = 1
\(W_p + W_a = 1\)
The plumber has worked for a total of \(5\) hours whereas, his apprentice worked for \(3\) hours only
i.e. \(\frac{5}{x} + \frac{3}{2x} = 1\)
\(13 = 2x\)
\(x = 6.5\)
Col. A: \(2(6.5) = 13\)
Col. B: \(10\)
Hence, option A
More efficient means less time or more work!
Let us assume it takes the plumber alone \(x\) hours to finish the job
So his apprentice would require \(2x\) hours to finish the same job
Work done by Plumber + Work done by the apprentice = 1
\(W_p + W_a = 1\)
The plumber has worked for a total of \(5\) hours whereas, his apprentice worked for \(3\) hours only
i.e. \(\frac{5}{x} + \frac{3}{2x} = 1\)
\(13 = 2x\)
\(x = 6.5\)
Col. A: \(2(6.5) = 13\)
Col. B: \(10\)
Hence, option A
