Arvind works 4 times as fast as Suresh. If Suresh can complete a work in 20 days alone, then find the number of days in which Arvind and Suresh can together finish the work.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 4.
Arvind works 4 times as fast as Suresh.
Time taken by Suresh = 20 days
⇒ Total work = Efficiency × Time
Let the efficiency of Suresh be 1 unit/day
⇒ Efficiency of Arvind = 4 unit/day
⇒ Total work = 1 × 20 = 20 units
Work done by Arvind and Suresh in a day = 4 + 1 = 5 units
Time taken by Arvind and Suresh to complete the same work = 20/(4 + 1) = 20/5 = 4 days