Problema Solution
At 3pm Mark left Pittsburg and drove towards Cleveland, 208 km away. At 3:30 pm Carole left Cleveland and headed towards Pittsburg, driving 2 km/h slower than MArk. If there cars passed each other at 4:30, how fast was each driving
Answer provided by our tutors
Let
v = Mark's average rate
v - 2 = Carole's average rate
d = 208 km the sum of the distance that each of them drove
4:30 - 3 = 1.5 hr is Mark's time
1.5 - 0.5 = 1 hr is Carol's time (since she started driving 30 min = 0.5 hr later)
Since distance = speed*time and the are driving in opposite directions we can write:
1.5*v + 1*(v - 2) = 208
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click here to see the equation solved for v
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v = 84 mph
v - 2 = 84 - 2 = 82 mph
Mark was driving with an average speed of 84 mph.
Carole was driving with an average speed of 82 mph.