Question

A builder appoints three construction workers Akash, Sunil and Rakesh on
one of his sites. They take 20, 30 and 60 days respectively to do a piece of
work. How many days will it take Akash to complete the entire work if he is
assisted by Sunil and Rakesh every third day?
1.10 days
2.15 days
3.25 days
4.30 days
5.45 days
​

Answer 1

Answer:

15 days is the right answer

Explanation:

Total work done by Akash, Sunil and Rakesh in 1 day = {(1/20) + (1/30) + (1/60)} = 1/10

Work done along by Akash in 2 days = (1/20) × 2 = 1/10

Work Done in 3 days (1 day of all three together + 2 days of Akash’s work) = (1/10) + (1/10) = 1/5

So, work done in 3 days = 1/5

Time taken to complete the work = 5×3 = 15 days

Answer 2

Answer:

The correct answer is

2) 15 days

Concept

This question tells us about the work done by everyone together takes less time and is completed easily.

Given

Days taken by Akash to complete work = 20 days

Days taken by Sunil to complete work = 30 days

Days taken by Rakesh to complete work = 60 days

Also, Akash is to complete the entire work by taking help of Sunil and Rakesh every 3rd day.

To find:

How many days will it take Akash to complete the entire work if he is assisted by Sunil and Rakesh every 3rd day

Explanation:

Days taken by Akash to complete work = 20 days

So, fraction of work completed by him in 1 day = 1/20

Days taken by Sunil to complete work = 30 days

So, fraction of work completed by him in 1 day = 1/30

Days taken by Rakesh to complete work = 60 days

So, fraction of work completed by him in 1 day = 1/60

Also, Akash is to complete the entire work by taking help of Sunil and Rakesh every 3rd day.

So there will be multiple cycle of 3 day in which Akash will work for all the three days and Sunil and Rakesh will work for 1 day only with Akash.

So fraction of work completed in 3 days cycle = 3*1/20 + 1*1/30 + 1*1/60

                                                                             = 3/20 + 1/30 + 1/60

                                                                             = (9+2+1)/60

                                                                             = 12/60

                                                                             = 1/5

At this rate total number of cycles required to complete the work = 1÷ 1/5

                                                                                                      = 5

As each cycle has 3 days,

total number of days required to complete the work = 3*5

                                                                                 = 15 days

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