Arin alone can do a piece of work in 6 days and Selvi alone can do the same in 8 days. Arin and Selvi undertook to do it for Rs. 7,200. With the help of Kevin, they completed the work in 3 days. How much is to be paid to Kevin?

Correct option is A

Solution:

Total Work = LCM of 6, 8 and 3 = 24 unit

Efficiency of Arin = $$\frac{24}6$$​ = 4 unit per day

Efficiency of Selvi = $$\frac{24}8$$​ = 3 unit per day

Efficiency of Kevin+ Arin+ Selvi = $$\frac{24}{3 }$$​= 8 unit per day

Efficiency of Kevin = 8 - 4-3 = 1unit

Share of Kevin = $$\frac38$$​ ×2400 = Rs.900