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HKD1710
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Working independently, Tina can do a certain job in 12 hours 27 Nov 2018, 09:06
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E
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91% (01:24) correct 9% (02:07) wrong based on 899 sessions

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Working independently, Tina can do a certain job in 12 hours. Working independently, Ann can do the same job in 9 hours. If Tina works independently at the job for 8 hours and then Ann works independently, how many hours will it take Ann to complete the remainder of the job?

(A) 2/3
(B) 3/4
(C) 1
(D) 2
(E) 3
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E
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Working independently, Tina can do a certain job in 12 hours 27 Nov 2018, 11:05
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HKD1710
Working independently, Tina can do a certain job in 12 hours. Working independently, Ann can do the same job in 9 hours. If Tina works independently at the job for 8 hours and then Ann works independently, how many hours will it take Ann to complete the remainder of the job?

(A) 2/3
(B) 3/4
(C) 1
(D) 2
(E) 3
 
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Work done by Tina \(\frac{8}{12}\)

Work left to be done \(\frac{1}{3}\)

Ann`s Rate \(\frac{1}{9}\)

To find how much time it will take for Ann to complete remainder of job divide work by rate

i.e \(\frac{\frac{1}{3}}{\frac{1}{9}}\) = \(\frac{1}{3} *\frac{9}{1}\) = \(3\)

IMO: E :)­
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Working independently, Tina can do a certain job in 12 hours 10 Feb 2019, 00:54
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HKD1710
Working independently, Tina can do a certain job in 12 hours. Working independently, Ann can do the same job in 9 hours. If Tina works independently at the job for 8 hours and then Ann works independently, how many hours will it take Ann to complete the remainder of the job?

(A) 2/3
(B) 3/4
(C) 1
(D) 2
(E) 3
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Rate of R = W/12 = 3 units/hr
Rate of A = W/9 = 4 units/hr

Let W = 36 units

R works for 8 hrs means work done = 24 units

Remaining work = 12 units

A works for 3 hrs for the remaining 12 units
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Working independently, Tina can do a certain job in 12 hours Updated on: 13 Feb 2019, 22:28
Originally posted by EgmatQuantExpert on 10 Feb 2019, 05:35.
Last edited by EgmatQuantExpert on 13 Feb 2019, 22:28, edited 1 time in total.
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Solution


Given:
    • Working independently, Tina can do a certain job in 12 hours.
    • Working independently, Ann can do the same job in 9 hours.
    • Tina works independently at the job for 8 hours and then Ann works independently.

To find:
    • The time taken by Ann, to complete the remainder of the job.

Approach and Working:
Let us assume the total job = LCM (12, 9) = 36 units

    • 1-hour job of Tina = \(\frac{36}{12}\) = 3 units
    • 1-hour job of Ann = \(\frac{36}{9}\) = 4 units

As Tina works for the first 8 hours, the amount of work done by Tina = 3 x 8 = 24 units

Hence, remaining job = 36 – 24 = 12 units
Therefore, the time taken by Ann = \(\frac{12}{4}\) = 3 hours

Hence, the correct answer is option E.

Answer: E

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Working independently, Tina can do a certain job in 12 hours 10 Feb 2019, 05:40
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HKD1710
Working independently, Tina can do a certain job in 12 hours. Working independently, Ann can do the same job in 9 hours. If Tina works independently at the job for 8 hours and then Ann works independently, how many hours will it take Ann to complete the remainder of the job?

(A) 2/3
(B) 3/4
(C) 1
(D) 2
(E) 3
 
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rate of Tina = 1/12
Rate of Ann = 1/9

so work done by tina n 8 hrs
x/12 * 8 = 2x/3
left = x/3
so Ann would take
x/3 * 9 = 3 hrs
x = 1
IMO E­
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Working independently, Tina can do a certain job in 12 hours 05 May 2025, 19:03
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