Question

1. A ,B and C can alone finish an assignment 10 days, 15 days and 20 days respectively. they decide to complete a work by working in turns. A  works alone on Monday, B does the work alone on Tuesday, followed by C working alone on Wednesday and so on. What proportion of the complete work is done by B? 
1. 4/9
2. 2/3
3. 1/3
4. 2/9

Answer 1

Correct Answer - Option 3 : 1/3

Given:

A finished work → 10 days

B finished work → 15 days

C finished work → 20 days

Calculations:

LCM of (10, 15, 20,) = 60

then the efficiency of A = 6, B = 4,and C = 3

A/Q 

      A B and C work alone

∴ A B and C work are done in 3 days → 6 + 4 + 3 = 13

Total work is 60 and A B and C are done 13 work in just 3 days 

⇒ A B and C are done work 13 × 5 = 65 work in five cyclic in 3 × 5 = 15 days 

Hence B work are work done 4 × 5 = 20 from total work of 60 

∴ B work 20/60 = 1/3 part