Question

Mike, an experienced bricklayer, can build a wall in 6 hours, while his son, who is learning, can do the job in 12 hours. How long, in hours and minutes, does it take for them to build a wall together? (Write your answer in mixed units. Enter a zero in any unneeded blanks.)

Answer 1

4 hours

Explanation

It called the together formula:

1/6 +1/12 because one bricklayer can build one wall in 6 hours and the other in 12

Then add them: 1/6 + 1/12 = 2/12+1/12 = 3/12 = 1/4

Time = 1/Combined Rate= 1/1/4 which equals 4

4 hours to build one wall