Question

A alone can make a chair in 40 days and B alone can make the same chair in 24 days. If A and B are working on alternate days and A works on the first day, then in how many days will the chair be completed?

• A. 34 days
• B. 32 days
• C. 28 days
• D. 30 days

Answer 1

Answer:

D. 30 days

Solution: Given: A can make the chair in days = 40 B can make the same chair in days = 24 Concept: In this type of question always imagine the total work as LCM of time taken by individuals to perform the work. Formula used: Efficiency = Total work/Time taken Calculation: Let the total work be LCM of 40, 24 i.e. 120 unit Efficiency of A = 120/40 = 3 unit/day Efficiency of B = 120/24 = 5 unit/day If they work on alternate days starting from A their 2 days work = 3 + 5 = 8 unit i.e. 8 units of work completed in 2 days So, (8 × 15) = 120 units of work be completed in (2 × 15) = 30 days ∴ The chair will be completed in = 30 days