Select the correct answerThe ratio of the efficiencies of A, B and C is 4 : 5 : 3. Working together, they can complete that work in 25 days. A and C together will complete 35% of that work in?Options12 days18 days15 days10 days

To solve this problem, we first need to understand the concept of efficiency in work problems. Efficiency is the ability to do work. If A is more efficient than B, A will take less time to do the same work than B.

Step 1: Calculate the total efficiency of A, B, and C. The ratio of their efficiencies is given as 4:5:3. So, the total efficiency is 4+5+3 = 12.

Step 2: Find out how much work they can do in one day. Since they can complete the work in 25 days, in one day they can do 1/25 of the work. This is their combined daily work rate.

Step 3: Find out the combined efficiency of A and C. From the ratio, we know that the efficiency of A is 4 and C is 3. So, the combined efficiency of A and C is 4+3 = 7.

Step 4: Calculate how much work A and C can do in one day. Since the total efficiency is 12, A and C's combined daily work rate is (7/12) * (1/25) of the work.

Step 5: Calculate the time taken by A and C to complete 35% of the work. If A and C can do (7/12) * (1/25) of the work in one day, they will take 1/[(7/12) * (1/25)] days to do the whole work. So, to do 35% of the work, they will take 0.35/[(7/12) * (1/25)] days.

After calculating the above expression, we will get the answer in days which should match one of the options given.