A man is driving from A to B . in total it took 4 hours. he drove half the distance at 80kph and the other half at 100kph. wat is the total distance of the journey??
thanks~
2007-02-14 16:58:19 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
its not a whole number...
THANKS PHILO`
2007-02-14 17:07:15 · update #1
btw where did the 800 come from?
2007-02-14 17:12:15 · update #2
time = dist/speed, so
(d/2)/80 + (d/2)/100 = 4
d/160 + d/200 = 4
(d/160)800 + (d/200)800 = 4(800)
5d + 4d = 3200
9d = 3200
d = 355 5/9 km.
2007-02-14 17:03:58 · answer #1 · answered by Philo 7 · 2⤊ 0⤋
80*t1=dist/2
100*t2=dist/2
80*t1 = 100*t2 -> 100/80 = t1/t2 -> 5/4 = t1/(4-t1) -> 20-5t1=4t1 -> t1=20/9
80*20/9 = dist/2->dist = 1600*2/9 =355.55555
2007-02-15 01:57:55 · answer #2 · answered by hbj 2 · 0⤊ 0⤋
235 km
2007-02-15 01:05:27 · answer #3 · answered by Anonymous · 0⤊ 0⤋