Question

A, B and C can complete a work in 16 days, 30 days and 45 days respectively. If B and C start the work and worked for 10 days after that C leaves. In how many days the remaining work will be completed by A and B?
1. 4.33
2. 5.5
3. 6.33
4. 4.63

Answer 1

Correct Answer - Option 4 : 4.63

Given: 

A, B and C can complete a work in 16 days, 30 days and 45 days respectively. If B and C start the work and worked for 10 days after that C leaves

Formula:

If A and B can together finish it in t days with A and B finishing the work in a and b days respectively,

1/a + 1/b = 1/t

Calculation:

Let total work be 720

Efficiency of A = 720/16 = 45

Efficiency B = 720/30 = 24

Efficiency C = 720/45 = 16

Let the remaining work will be finished by A and B in n days

⇒ (24 + 16) × 10 + (45 + 24) × n = 720

⇒ 400 + 69n = 720

⇒ n = 4.63 days