A man can dig a hole in 5 hours. His son can dig the same size hole in twice the time his father takes. How long would it take them to dig the hole if they worked together?
2006-11-25 00:42:33 · 7 answers · asked by 2_right 2 in Environment
Suppose there is a volume of X to be dug.
The man digs at a rate of X/5 per hour and the son digs at a rate of X/10 per hour.
Working together they dig at a rate of X/5 + X/10 = 3X/10 per hour
Time taken is T = Total Volume/Rate
T = X/(10/3X) = 10/3 hours or 3hours and 20 min.
2006-11-25 00:48:58 · answer #1 · answered by migelito 5 · 1⤊ 0⤋
7 1/2 hours,the boy will slow the man down
2006-11-25 08:46:20 · answer #2 · answered by Nuthin_Fancy 2 · 0⤊ 0⤋
3 hrs 20 min
2006-11-25 08:45:27 · answer #3 · answered by draftboyg 4 · 1⤊ 0⤋
5 hrs
2006-11-25 08:45:02 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Wouldn't they get in eachother's way?
2006-11-25 08:45:53 · answer #5 · answered by dot&carryone. 7 · 0⤊ 0⤋
7.5 hours
2006-11-25 11:12:08 · answer #6 · answered by Tom 1 · 0⤊ 0⤋
Who gives a rat's butt ?
2006-11-25 09:22:25 · answer #7 · answered by the_lipsiot 7 · 0⤊ 0⤋