Question

Anil alone can do a job in 20 days while Sunil alone can do it in 40 days. Anil starts the job, and after 3 days, Sunil joins him. Again, after a few more days, Bimal joins them and they together finish the job. If Bimal has done 10% of the job, then in how many days was the job done?

• A. 14
• B. 13
• C. 15
• D. 12

Answer 1

Answer: (B)

13

Answer 2

Let the total work be 40 units.
The amount of work done by Anil in one day is $\frac{40}{20}=2$ units.
Similarly, the amount of work done by Sunil in one day is $\frac{20}{20}​=1$ unit.
Bimal contributes 10% of the work, which is 4 units. The remaining work is $40−4=36$ units and is done by Anil and Sunil.

Let's denote the number of days Anil took as $x$. Therefore, Sunil took $x−3$ days.
The equation representing the work done is $2x+(x−3)=36.$
Solving for x :
$2x+x−3=36$
$3x=39$
$x=13$

Therefore, Anil took 13 days to complete the work.