A welder requires 24 h to do a job. After the welder and an apprentice work on t

Question

A welder requires 24 h to do a job. After the welder and an apprentice work on the job for 12h, the welder quits. The apprentice finishes the job in 11h. How long would it take the apprentice, working alone, to do the job? Three machines are filling water bottles. The machines can fill the daily quota of water bottles in 42 h, 48 h, and 56 h, respectively. How long would it take to fill the daily quota of water bottles with all three machines working? One pipe can fill a tank in the tank in 5 h, and a third pipe can fill the tank 28 h. How long would it take to fill the tank with all three pipes operating?

Explanation / Answer

welder(w) finishes in 24 hrs

apprentice (a)

w +a work together for 12 hrs

Remaing work apprentice(a) finishes in 11hrs

Let a finishes worj in x hrs alone

So, a +w together would finish in 24x/(x+24) hrs

In 12 hrs = 12*(x+24)/24x = (x+24)/2xof work is completed

Reamining work = 1 - (x+24)/2x = ( x -24)/2x

So, x hrs a finishes 1 work

So, ( x -24)/2x of work a would finish in x[(x-24)/2x] = (x -24)/2 hrs

Given : Remaing work apprentice(a) finishes in 11hrs

(x -24)/2 =11

x -24 = 22

x = 46 hrs apprentice would finish work alone

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