Asked by Mo
Anthony leaves kingstons at 2:00 pm and drives to queensville, 160mi distant, at 45 mph. At 2:15 pm Helen leaves queensville and drives to kingston at 40mph. At what time do they pass each other on the road?
Answers
Answered by
Steve
If we place Kingston at (0,0) and Queensville at (0,160), then a time t from when Anthony left, the positions will be equal:
45t = 160-40(t - 1/4)
t = 2
So, they meet at 2:00+2 = 4:00 pm
Or, consider it like this. In the first 15 minutes, Anthony went 45/4 miles. The two cars are approaching each other at 85 mi/hr, so how long does it take to cover the remaining distance?
(160-45/4)/85 = 7/4
That is, they meet 7/4 hours after Helen started.
45t = 160-40(t - 1/4)
t = 2
So, they meet at 2:00+2 = 4:00 pm
Or, consider it like this. In the first 15 minutes, Anthony went 45/4 miles. The two cars are approaching each other at 85 mi/hr, so how long does it take to cover the remaining distance?
(160-45/4)/85 = 7/4
That is, they meet 7/4 hours after Helen started.