4 workers working 6 hours per day can finish painting a wall in 21 days. If 7 workers work for 4 hours per day, in how many days will they be able to finish the same work?

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RRB ALP CBT I 29 Aug 2018 Shift 2 Official Paper
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  1. 28
  2. 24
  3. 32
  4. 18

Answer (Detailed Solution Below)

Option 4 : 18
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Detailed Solution

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Given:

4 workers working 6 hours per day can finish painting a wall in 21 days.

Concept used:

Total work = M × D × H

Here,

M = No. of mens

D = No. of days

H = Hours taken each day

Calculation:

Total work = 4 × 6 × 21

⇒ 504

Let time taken by the 7 workers be x days

Now,

7 × 4 × x = 504

⇒ 28x = 504

⇒ x = 18

So, they will finish the work in 18 days

∴ The required answer is 18.

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