Isha can do a certain piece of work in 15 days. Isha and Smriti can together do the samework in 11 days, and Isha, Smriti and Ashlesha can do the same work together in 10 days. In how many days can Isha and Ashlesha do the same work

Correct option is D

Given:

Isha can do the work in 15 days.

Isha and Smriti together can do the work in 11 days.

Isha, Smriti, and Ashlesha together can do the work in 10 days.

Formula Used: ​

Total work = Efficiency $$\times$$ time​

Solution:​

Total Work = LCM of (15 , 11, 10) = 330 

Isha's work rate = $$\frac{330}{15} =22$$

Isha + Smriti  work rate = $$\frac{330}{11} =30$$ 

Isha + Smriti + Ashlesha work rate = $$\frac{330}{10} =33$$

Smriti's work rate = 30 - 22 = 8 

Now, 

Isha + Ashlesha work rate = 33 - 8 = 25 

Now, 

Time taken by Isha + Ashlesha to complete the whole work;

= $$\frac{330}{25} = \frac{66}5$$ days​