A is 20% more efficient than B and C is 25% less efficient than B. Working together A, B and C can complete the work in 20 days. How many days will A need to do 80% of the work?
Answer & explanation
Correct answer: option 2
Ratio of efficiency of A : B : C
100 : 120
100 : 75
___________________________________
10 : 12 : 9
Total work = efficiency x no. of days
= 31 x 20 = 620
Time taken by A to complete 80% of the work = \(\frac{80}{100}\) x \(\frac{Total\; work}{Efficiency}\)
= \(\frac{4}{5}\) x \(\frac{620}{10}\) = \(\frac{248}{5}\) = 49 \(\frac{3}{5}\) days