Question : A, B and C can do a piece of work in 20 days, 30 days and 60 days respectively. If A works daily and on every third day B and C also work with A, then in how many days, will the work be completed?
Option 1: 21
Option 2: 18
Option 3: 12
Option 4: 15

Question

Question : A, B and C can do a piece of work in 30 days, 45 days and 90 days, respectively. A starts the work and he is assisted by B and C together on every third day. In how many days will the work be completed?
Option 1: 23
Option 2: 24
Option 3: 30
Option 4: $22 \frac{1}{2}$

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Answer 1

Correct Answer: 15

Solution : The rates at which A, B, and C can complete the work are $\frac{1}{20}$ , $\frac{1}{30}$ , and $\frac{1}{60}$ of the work per day, respectively.
In a cycle of three days, A works for three days, B works for one day, and C works for one day. So, the total work done in three days is $= 3 \times \frac{1}{20} + 1 \times \frac{1}{30} + 1 \times \frac{1}{60}$
$= \frac{3}{20} + \frac{1}{30} + \frac{1}{60} = \frac{3}{20} + \frac{1}{30} + \frac{1}{60}$
$= \frac{9}{60} + \frac{2}{60} + \frac{1}{60}$
$= \frac{12}{60}$
$= \frac{1}{5}$
So, in three days, they complete $\frac{1}{5}$ of the work.
Therefore, the work will be completed in $5 \times 3 = 15$ days.
Hence, the correct answer is 15.

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Question : A, B and C can do a piece of work in 20 days, 30 days and 60 days respectively. If A works daily and on every third day B and C also work with A, then in how many days, will the work be completed?Option 1: 21Option 2: 18Option 3: 12Option 4: 15

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Question : A, B and C can do a piece of work in 20 days, 30 days and 60 days respectively. If A works daily and on every third day B and C also work with A, then in how many days, will the work be completed?
Option 1: 21
Option 2: 18
Option 3: 12
Option 4: 15