Original post and response from June of 2015 are in the quotes below:
A car and a truck were traveling to Town Q at constant average speeds. The car overtook the truck when they were 420 km from Town Q. The car arrived at Town Q at 6:30 p.m. while the van was still 120 km away from Town Q. The van arrived at Town Q at 8:30 p.m. What was the average speed of the car?
I am unable to get to the answer, please help. Thanks.You don't know when they started, but that's okay, because you know they were at the same point when the car caught up to the truck. Also, the fact that the car "overtook" and arrived first tells you which vehicle was faster.
The general methodology for this sort of exercise is fairly straightforward. (link)
In this case, things are actually simpler. You are given that the car covered 420 kilometers by a certain time. The truck had covered only 420 - 120 = 300 km in that same time, and required another two hours to cover the remaining 120 km. If it took two hours to cover 120 km, what was the truck's rate, in kph?
Given this rate of speed, how long, in total, did the truck take to cover the entire 420 km? Then at what time were the car and the truck side-by-side on the freeway?
Then at what time did the car meet up with the truck? So how long did the car take to cover the 420 km? Then what was the car's rate of speed?
If you get stuck, please reply showing your work in answering the above questions. Thank you!
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