Multiple choice

5 skilled workers can build a wall in 20days: 8 semi-skilled workers can build a wall in 25 days; 10 unskilled workers can build a wall in 30days. If a team has 2 skilled, 6 semi-skilled and 5 unskilled workers, how long will it take to build the wall?

  1. 20

  2. 18

  3. 16

  4. 15
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For skilled: men -> days -> amount of wall

5 -> 20  -> 1
1 -> 100 -> 1
1 -> 1   -> 1/100
For semi-skilled: men -> days -> amount of wall

8 -> 25  -> 1

1 -> 200 -> 1
1 -> 1   -> 1/200
For unskilled: men -> days -> amount of wall

10 -> 30  -> 1

1  -> 300 -> 1
1  -> 1   -> 1/300
Amount of work 2 skilled in 1 day = 2/100 Amount of work 6 semi-skilled in 1 day = 6/200 Amount of work 5 unskilled in 1 day = 5/300

Total work in 1 day 

= 2/100+6/200+5/300
= 12/600+18/600+10/600
= 1/15

So complete work will take 15 days

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