Question

Two men and a piece of work in 6 hours and 4 hours respectively. After the first has worked for 2
hours, le is joined by the other. By when should the work be completed ?​

Answer 1

1st person in 6 hours can complete 1 full work
son in 1 hour he can complete 1/6 part of work
in 2 hours he can complete 2/6 or 1/3rd of work
so work left is 1 - 1/3 or 2/3 Rd of work
now 2nd person in 4 hours can complete 1 full work
so in 1 hour he can complete 1/4th of work
so in 1 hour both of them can do 1/6 + 1/4 = 5/12 part of work
So 5/12 part work can be completed in 1 hour
So 1 full work can be done in 12/5 hour
2/3 Rd work can be done in 12/5×2/3 hours= 4/5 hour=in 45 min.