A and B can complete a piece of work in 25 days and 55 days, respectively. The total number of days (in whole number) to complete the work, if A and B both work together, is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 18.
Work done by A in one day = 1 / 25
Work done by B in one day = 1 / 55
Work done by A and B together in one day = (1 / 25) + (1 / 55)
⇒ Work done by A and B together in one day = (1)/(25) + (1)/(55)
⇒ Work done by A and B together in one day = (55 + 25)/(25 × 55)
⇒ Work done by A and B together in one day = (80)/(1375)
⇒ Work done by A and B together in one day = (16)/(275)
Total time to complete the work = 1 / ((16)/(275))
⇒ Total time to complete the work = (275)/(16)
⇒ Total time to complete the work = 17.1875 days
Rounding to the whole number, total time = 18 days