If first person is n times efficient than the second person , then the time taken to complete a work by
first person : second person = 1 : n
∴ Time to complete the work by Anil and Bharat = k : 2k
According to the question ,
Time taken by Bharat - Time taken by Anil = 30 min
⇒ 2k - k = 30
⇒ k = 30
Time required by Anil = 30 min
Time required by Bharat = 60 min
∴ Time required to finish the work when they work together
=
= 20 min