Question 12

Working alone, A can do a job in 15 days and B can do the same job in 18 days. In how many days will the job be completed if both work together?

A can do (1/15) part of job in 1 day.

and B can do (1/18) part of job in 1 day.

So,in 1 day they together can do

$$(1/15)+(1/18)=(6+5)/90=11/90$$

part of job.

So, they together can do full job in 90/11 days.

So,E is correct choice.

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