Question

Sunny, nikki and rohan are working on their dream project after 4 days of working they had an argument. so that, sunny left the work. Remaining work is continued by nikki and rohan. Nikki left the work 2 days before its completion the project. In how many days work is completed if sunny, nikki and rohan separately complete the project in 15, 20 and 30 days respectively
1. 6
2. 4
3. 8
4. 10
5. 12

Answer 1

Correct Answer - Option 4 : 10

Given

Sunny, Nikki and Rohan separately complete the project in 15, 20 and 30 days respectively 

Concept used

Work = time × efficiency

Calculation 

LCM of 15, 20 and 30 = 60  i.e, total work = 60 units 

Efficiency of Sunny = 4 units / per day 

Efficiency of Nikki = 3 units / per day 

Efficiency of Rohan = 2 units / per day 

They altogether work for 4 days , so total work done in 4 days = 36 units 

Remaining work is completed by Nikki and Rohan but before 2 days of completion Nikki left work 

So, Rohan worked separately for 2 days  = 4 units 

Remaining work = 60 - 40 = 20 units 

This 20 units was done by Nikki and Rohan in = 20/5 = 4 days 

So, whole project was completed in = 4 + 2 + 4 = 10 days

∴ 10 days are required to complete the whole work.