How long would it take michael to cut the grass if he worked by himself?

Question

john can cut the grass in 4 hours by himself. When john cuts the grass with his younger brother miacheal. it takes 3 hours. How long would it take Michael to cut the grass if he worked by himself?

Answer 1

John cuts the grass = 4hours

John and Michael cuts the grass = 3 hours

It takes John 1 hour less to cut the grass

Thus, 2 persons cut the grass = 3 hours

Therefore 1 person working together  = 3 hours / 2 persons

                                                      = 1.5 hours

But if Michael cuts grass by himself =  1.5 hours + 1.5 hours

                                                   = 3 hours

 

Answer 2

Working 3 hours John cuts 3/4 of the grass.

Michael cuts the other 1/4 in three hours.

Working alone Michael would need 4(3) or 12 hours.