A works twice as fast as B and B works twice as fast as C. All three working together can finish a task in 4 days with the help of D. If D alone can finish the same task in 16 days, then in how many days will A alone finish 75% of the same task?
Answer & explanation
Correct answer: option 4
Given,
A : B : C
Efficiency 4 : 2 : 1
According to the question,
⇒ (7 + D) x 4 = D x 16
⇒ D = \(\frac{7}{3}\) (Efficiency)
⇒ Total work = 16 x \(\frac{7}{3}\) = \(\frac{112}{3}\) units,
⇒ A alone can finish 75% of the work in
⇒ \(\frac{3}{4}\) x \(\frac{112}{3}\) x \(\frac{1}{4}\) = 7 days.
Therefore, A alone can finish the total work in 7 days.