Question

L completes a work two times faster than M .if both work together they complete the work in 40 days.then, find the time taken by L alone.
1. 120 days
2. 20 days
3. 50 days 
4. 60 days

Answer 1

Correct Answer - Option 4 : 60 days

Given

L is two times efficient than M

Calculation

Let the time taken by L is x days

So, time taken by M is 2x days

Work done by L in 1 day = (1/x)

Work done by M in 1 day = (1/2x)

According to question

(1/x) + (1/2x) = (1/40)

⇒ (2 + 1)/2x = 1/40

⇒ 3/2x = 1/40

⇒ x = (3 × 40)/2

⇒ x = 60 days

∴ Time taken by L is 60 days.