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Adam completes 60% of a task in 15 days and then takes the help of Bob

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Bunuel
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Adam completes 60% of a task in 15 days and then takes the help of Bob [#permalink] Adam completes 60% of a task in 15 days and then takes the help of Bob   03 Jan 2022, 06:15
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72% (02:36) correct 28% (02:51) wrong based on 68 sessions
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Adam completes 60% of a task in 15 days and then takes the help of Bob and Carol. Bob is 50% as efficient as Adam is and Carol is 50% as efficient as Bob is. In how many more days will they complete the task?

A. \(13\frac{1}{3}\) days

B. \(8\frac{2}{3}\) days

C. \(5\frac{5}{7}\) days

D. \(7\frac{5}{7}\) days

E. 5 days
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Ijajkhan
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Re: Adam completes 60% of a task in 15 days and then takes the help of Bob [#permalink] Adam completes 60% of a task in 15 days and then takes the help of Bob   07 Jan 2022, 23:21
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Adam finishes 60% = 15 days
So, 40% = 10 days

As Bob is 50% efficient as Adam,
He would take → 20 days to finish 40%.
Similarly, Carl would take → 40 days.

By working together, the would take =
Efficiency→ 4+2+1/40←Total work (LCM)
= 7/40
They will take = 40/7 = 5 5/7 days more

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Re: Adam completes 60% of a task in 15 days and then takes the help of Bob [#permalink] Adam completes 60% of a task in 15 days and then takes the help of Bob   14 Aug 2022, 06:01
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First, take the simplest option of 5 days into consideration.
Adam would do 20% work in those 5 days.
Bob would do 10% work in those 5 days.
Carol would do 5% work in those 5 days.
Total = 60+20+10+5 = 95% work
So the next closest option to 5 days would be a sensible choice.
Hence 5 (5/7) days
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Re: Adam completes 60% of a task in 15 days and then takes the help of Bob [#permalink] Adam completes 60% of a task in 15 days and then takes the help of Bob   16 Aug 2022, 09:44
Lets say Adam completes 30 units in 15 days, so total units = 50 units (30*100/60)
So, A does 2 units / day
B does 1 unit / day
C does 0.5 unit / day

In total 3.5 units / day, so for remaining 20 units they will take - 20/3.5 days which comes to approximately >5 days. Hence C
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Re: Adam completes 60% of a task in 15 days and then takes the help of Bob [#permalink]
16 Aug 2022, 09:44
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Bunuel
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