Anna paints a fence in 4 hours wile her brother paints it in 5 hours. If they work together, how lon

Discussion in 'Calculator Requests' started by math_celebrity, Nov 25, 2022.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    Anna paints a fence in 4 hours wile her brother paints it in 5 hours. If they work together, how long will it take them to paint the fence?

    Set up unit rates per hour:
    • Anna paints 1/4 of a fence per hour
    • Brother paints 1/5 of a fence per hour
    • Combined, they paint 1/4 + 1/5 = 9/20 of a fence per hour
    Setup a proportion of time to hours where h is the number of hours needed to paint the fence
    9/20 of a fence the first hour
    18/20 of a fence the second hour
    2/20 is left. Each 1/20 of the fence takes 60/9 = 6 & 2/3 minutes
    6 & 2/3 minutes * 2 = 13 & 1/3 minutes

    Final time is:
    2 hours and 13 & 1/3 minutes
     

Share This Page