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| 1. | A and B can finish a piece of work in 16 days and 12 days respectively. A started the work and worked at it for 2 days. He was then joined by B. Find the total time taken to finish the work. | 
| Answer» we know that, Number of days A required to do piece of work = 16 days Number of days B required to do piece of work = 12 days ∴ We can calculate, work done by A in 1 day = 1/16 Work done by B in 1 day = 1/12 A alone works for 2 days and the work completed by A in 2 days = 2 × 1/16 = 1/8 ∴ work left = 1- 1/8 = 7/8 Work done by A, B together in a one day = 1/16 + 1/12 = 7/48 ∴ they can work together in 48/7 days But 7/8th work is completed by both A and B ∴ time required to complete 7/8th work together by A and B = 7/8 × 48/7 = 6 days Time taken to finish the work = 6 + 2 = 8 days(2 is added because 1/8 work is done by A alone) ∴ Total time taken to complete the work = 8 days. | |