Question

Kim can wash 150 window panes in 3 hours. Gary can wash 110 window panes in 2 hours. Kim and Gary work together to wash a total of 290 window panes. If they continue to wash at the same rate, how long will it take them to wash the 290 window panes? Give your answer in hours and minutes, to the nearest minute.​

Answer 1

2 hours and 38 minutes.

Explanation:

First we need their hourly rates.

• Kim washes 50 windows per hour.
• Gary washes 55 windows per hour.

all you have to do now is some adding and dividing:

`50+55=105\\[so together, they wash 110 windows.]\\\\290/110=2.6363636363\\[we can further simplify that to get the hours/minutes format you need:]\\2.63...\\ [turns into] 2\\[hours and] 38 \\[minutes.]`________________________

`2.63636hr=2[hr]+0.63636[hr]\\0.63636hr*60 [mins, 1hr]=38.182min\\38.182min=38min+0.182min\\0.182min*60s1min=10.92s\\10.92s=11s\\[Combining:] 02:38:11\\\\[`