B would have taken 10 hours more than what A would have taken to complete a task. Working together they can complete the task in 12 hours. How many hours would B take to do 50% of the task?
Answer & explanation
Correct answer: option 2
let A takes n hours, B will take (n+10) hours to do the same work.
together they can complete the same work in 12 hours.
In 1 hour, A and B together do
\(\frac{1}{n}\) + \(\frac{1}{n + 10}\) = \(\frac{1}{12}\)
12(n+10) + 12n = n(n+10)
on solving
n = 20. [Note: n = -6 is not possible ]
So A does the work in 20 hours and B done in (20+10) = 30 days
if B does whole work in 30 days then 50% of work will be done in 15 days.