SOLUTION: At 9:30 car a started its journey at 65 km/h. At 11:00 car B started its journey and travelled at the same road as car a. If car b took 5 hours to catch up with car a find the spee

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Question 1154679: At 9:30 car a started its journey at 65 km/h. At 11:00 car B started its journey and travelled at the same road as car a. If car b took 5 hours to catch up with car a find the speed of car b.
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52786) About Me  (Show Source):
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From 9:30 am to 11:00 am, car A covered 65 km/h * 1.5 hours = 97.5 km.


Now let start count the time from the moment of 11:00 am: we have two cars moving.


The distance traveled by car A to the moment of time 11:00 am + 5 hours = 4:00 pm is

    97.5 + 5*65 kilometers = 422.5.


So, the car B covered this distance in 5 hours.


Hence, the car B' speed was  422.5%2F5 = 84.5 kilometers.    ANSWER

Solved.

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Answer by greenestamps(13200) About Me  (Show Source):
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The first car travels for 1.5 hours at 65mph before the second car starts. In that time it travels 65*1.5 = 97.5 miles.

The second car has to make up those 97.5 miles in 5 hours; the rate at which it must catch up to the first car is 97.5/5 = 19.5 miles per hour.

So the speed of the second car must be 19.5mph faster than the speed of the first car: 65+19.5 = 84.5mph.