Question 484810: Daddy Lanz and his daughter shin leave home at the same time in separate automobiles. Daddy Lanz drives to his office, a distance of 24 km, and shin drives to school, a distance of 28 km. They arrive at their destinations at the same time. What are their Average rates, if daddy lanz's average rate is 12km/hr less than shin's?
Answer by htmentor(1343)   (Show Source):
You can put this solution on YOUR website! Daddy Lanz and his daughter shin leave home at the same time in separate automobiles. Daddy Lanz drives to his office, a distance of 24 km, and shin drives to school, a distance of 28 km. They arrive at their destinations at the same time. What are their Average rates, if daddy lanz's average rate is 12km/hr less than shin's?
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Let R = Shin's rate
Then Daddy's rate = R - 12
Since rate = distance/time, and they arrive at the same time, the two rate equations are:
R = 28/t
R - 12 = 24/t
where t = the travel time
Solve for t in the 1st equation:
t = 28/R
Substitute into the 2nd equation:
R - 12 = 24/(28/R)
R - 12 = 24R/28
(4/28)R = 12
This gives R = 84 km/hr
Therefore, Daddy's rate = 84 - 12 = 72 km/hr
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