If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?
TIA!!
2007-05-09 13:58:36 · 5 answers · asked by Curious 1 in Science & Mathematics ➔ Mathematics
I know the answer is 2 hours and 24 minutes, but I don't know how to get the answer.
2007-05-09 14:11:15 · update #1
Let area to be covered = X units²
Sally`s rate of working = X / 4 units² / h
John`s rate of working = X / 6 units² / h
In 1 h both will cover X/4 + X/6 units²
= 3X/12 + 2X/12 units²
= 5X/12 units²
5X/12 units²<-------> 1 h
X units²<------> X / (5X/12) h
= 12/5 h
= 2 and 2/5 h
= 2h 24 mins
2007-05-10 02:05:16 · answer #1 · answered by Como 7 · 0⤊ 0⤋
a million/4 = area painted by potential of Sally in a million hour a million/6 = area painted by potential of John in a million hour a million/4 + a million/6 = area painted together in a million hour. time together = a million/(a million/4 + a million/6) = a million/(3/12 + 2/12) = a million/(5/12) = 12/5 hrs = 2 2/5 hrs = 2 hrs 24 min
2016-11-26 23:02:28 · answer #2 · answered by Anonymous · 0⤊ 0⤋
It has to be less than 4 hours. The answer is 2 hours and 12 minutes.
2007-05-09 14:26:01 · answer #3 · answered by Pandelis X 1 · 0⤊ 0⤋
two and a half hours
4/4 + 6/4 = 10/4
10/4 = 2.5 hours
2007-05-09 14:10:14 · answer #4 · answered by Anonymous · 0⤊ 0⤋
?wouldnt it just be the average.. so 4+6/2=5 hours
2007-05-09 14:07:05 · answer #5 · answered by Ashley 3 · 0⤊ 1⤋