Clem started biking at 18 km/h at 9:00 Helena started biking 30 min. later at 20/h in the same direction.
a) at what time did helena overtake Clem?
b) how long had each biker been on the road when Helena overtook Clem?
2007-06-10 05:57:06 · 5 answers · asked by sweet_pomelo 2 in Science & Mathematics ➔ Mathematics
a)
Clem: 18km/h, 9am, time = t + 0.5 hr
Helena: 20km/h, 9.30am, time = t hr
Distance = speed x time
Distance of Clem = Distance of Helena
18(t+0.5) = 20t
18t + 9 = 20t
9 = 2t
t = 9/2
t = 4.5 hours
4.5 + 0.5 = 5 hours
9am + 5 hours = 1400 hours = 2pm
b) Clem had been on the road for 5 hours and Helena had been on the road for 4.5 hours.
2007-06-10 06:05:11 · answer #1 · answered by Kemmy 6 · 0⤊ 0⤋
18 t = distance Clem travels
20 (t-.5) = distance Helena travels
18t = 20(t-.5)
18t =20 t -10
-2t = -10
t = 5
So Helena overtook Clem at 2:00 PM
Clem was on the road 5 hours
Helena was on the road 4.5 hours.
2007-06-10 06:12:02 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋
A: 2:00
B: Clem, 5 hours; Helena 4 1/2 hours
2007-06-10 06:11:18 · answer #3 · answered by Jon F 1 · 0⤊ 0⤋
Ask yourself these questions:
1. How much farther ahead was Clem when Helena started?
2. How many km can Helena make up in one hour?
Divide the answer to 1. by the answer to 2.
Aww... I can't believe everyone gave you the answer!
2007-06-10 06:09:27 · answer #4 · answered by Deltaman 2 · 0⤊ 0⤋
let helena take t hours to overtake clem.
18(1/2+t)=20t
9+18t=20t
2t=9
t=4.5 hours
t
2007-06-10 06:04:09 · answer #5 · answered by Anonymous · 0⤊ 0⤋