Bicyclists Bob and Judy started at noon from points 60km apart and rode toward each other, meeting at 1:30pm. Judy's speed was 4km greater than Bob's speed. Find their speeds.
2006-09-10 12:16:17 · 4 answers · asked by islAnd_paradisex4 1 in Science & Mathematics ➔ Mathematics
Bob-- xkm per hour
Jud-- x+4km per hour
x*1.5+(x+4)*1.5=60
3x+6=60
3x=54
x=18
Bob 18km per hour
Judy 22km per hour
2006-09-10 12:23:38 · answer #1 · answered by Anonymous · 0⤊ 0⤋
In an hour and a half they rode an average of 30 km each, or about 20 km/h, so I guess Judy was going 22 and Bob 18 km/h
2006-09-10 19:20:18 · answer #2 · answered by Random Precision 4 · 0⤊ 0⤋
There is a different solution... without using equations:
They spent 1.5h to meet each other.
In this time Judy rode 1.5hx4km/h = 6km more than Bob
60km - 6km = 54km is the total space rode without the difference
54km/2 = 27km is the same space for each one
Bob space is ; 27km
Judy space is 27km + 6km = 33km
Speed is the quotient space/time
So, Bob speed 27km/1.5h = 18km/h
Judy speed 33km/1.5h = 22km/h
2006-09-10 20:01:22 · answer #3 · answered by vahucel 6 · 0⤊ 0⤋
Isn't it interesting that (unless they re-arranged their answers for effect) Random Precision took an overall view and adjusted the average to get the answer; while CanCan went straight to exact parameters and got the same answer in several steps.
Of course CanCan may have also seen the overall picture but thought the student (and teacher) would want the steps shown.
They both should get best answer.
2006-09-10 19:48:12 · answer #4 · answered by fata minerva 3 · 0⤊ 0⤋