Question

Arun and Rahul started working together and complete a work in 12 days if the efficiency of arun is increased by 40% and the efficiency of rahul decreases by 20% then they complete the same work in 10 days find the time in which Rahul can complete the same work alone?​

Answer 1

In 36 days, Rahul can finish the Work

Step-by-step explanation:

Let the efficiency of Arun be a unit/day and

The efficiency of Rahul be r unit/day

Now, the when they are working together = (a + r) x 12  

Efficiency of Arun increases by 40% i.e. 1.4 x a  

Efficiency of Rahul decreased by 20% = 0.8 x r

hence, According to Question,  

(a + r) x 12 = (a x 1.4 + r x 0.8) x 10

12a + 12r = 14a + 8r

2a = 4r

a/r = 2/1

Therefore, Efficiency of Arun and Rahul together = 3 units/day

Total Work = 3 x 12 = 36 units

Time in which Rahul alone can complete the work = 36/1 = 36 days

So, Rahul can complete the work in 36 days!