Question

the two motor mechanics, Azim and Kazim, working together can overhaul a scooter in 6 hours.Azim alone can do a job in 18 hours.In how many hours can Kazim alone do it?

Answer 1

Work done by both together in 6hrs = X (say)
Now, Work done by Azim in 18 hrs = x₁ (say)
so, work done by Azim in 1hr = x₁/18

Similarly, Work done by Kazim in t hrs = x₂ (say)
so, work done by Kazim in 1hr = x₂/t

Here comes a concept of functional reciprocation that , if less people work then time taken will be more and vice-versa

So, 1/18 + 1/t = 1/6
=> 1/t = 1/6 -1/18 = (3-1)/18 = 2/18
=> 1/t = 1/9
On cross multiplying , we obtain that
t = 9
Hence, Kazim will take 9hrs alone to complete the same amount of work .



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