Discussion :: Time and Work
- A and B can complete a wall in 15 and 20 hours respectively. If they work together, the wall is completed in 12 hours and they use 280 less bricks. Find the total number of bricks in the wall.
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Answer : Option A
Explanation :
Note: Assume the total work = LCM of the given time
Take the LCM of hours = LCM of (15 and 20) = 60
Let the total bricks = 60
Note: One hour work = (total work/ time)
A's one hour work = 60/15 = 4 bricks
B's one hour work = 60/20 = 3 bricks
(A+B)'s one hour work = 4+3 = 7 bricks....................... (i)
But, ATQ
(A+B)'s one hour work = 60/12 = 5 bricks.................... (ii)
The difference between equation i and ii = 2 bricks/hour
But, ATQ it is 280 bricks
i.e., multiple of 140
So, multiply the total work with 140
Hence, 60* 140 = 8400 bricks
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