SOLUTION: Hi A black car travelled from a to c at 60km per hour. A blue car took 4 hours to travel the same distance. Both cars passed b at 2pm and the blue car reached c at 3pm. If b was

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Question 1201052: Hi
A black car travelled from a to c at 60km per hour. A blue car took 4 hours to travel the same distance. Both cars passed b at 2pm and the blue car reached c at 3pm. If b was 80km from c , what time did the black car leave a .
Thanks
Found 2 solutions by mananth, MathTherapy:
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Blue car takes 1 hour to reach from b to c which is 80 km distance.
So speed of bue car = 80 km/h.
It takes 4 hours from a to c
Distance = speed into time
so the distance from a to c is 80*4 = 320 km
Blue car leaves at 11.00 to reach c at3.00 pm. ( 4 hours)

Black car speed = 60 km/h
time taken by black car = 320/60 = 5.33 hours
So it has left 1.33 hours before blue car

Answer by MathTherapy(10551) About Me  (Show Source):
You can put this solution on YOUR website!
Hi
A black car travelled from a to c at 60km per hour. A blue car took 4 hours to travel the same distance.  Both cars passed b at 2pm and the blue car reached c at 3pm. If b was 80km from c , what time did the black car leave a .

Thanks

He's WRONG!!!!

Blue car took 4 hours to get from a to c, got to c at @ 3:00 p.m., so it left "a" 4 hours before 3:00 p.m. or at 11:00 a.m.
Blue car passed b at 2:00 p.m., and got to c at 3:00 p.m., so it took 1 hour to get from b to c, which means that it took
3 hours to travel from a to b. As it's 80 km from b to c, and blue car took 1 hour for the trip, blue car's speed, from b
to c, was 80(1) = 80 km/h. That was also its speed from a to b.

Now, since blue car's speed was 80 km/h, and it took 3 hours to travel from a to b, then distance from a to b is 80(3) = 240 km.

With a speed of 60 km/h, the distance from a to b being 240 km, the black car's time taken to travel 240 km from a to b, would be 240%2F60 = 4 hours.

Since the black car took 4 hours to travel from a to b, it's obvious that the black car left "a" 4 hours before arriving at b, or 4 hours before 2:00 p.m. which was: 10:00 a.m.