SOLUTION: Kelly drove north for 12 miles and then east for 9 miles at an average rate of 42 miles per hour to arrive at the town of Prime. Brenda left from the same location, at the same tim

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Question 412454: Kelly drove north for 12 miles and then east for 9 miles at an average rate of 42 miles per hour to arrive at the town of Prime. Brenda left from the same location, at the same time, and drove along a straight road to Prime at an average 45 miles per hour. How many minutes earlier than Kelly did Brenda arrive?
I first tried drawing a diagram,then I tried using the formula d=rt, and I am not able to produce an anwer that makes sense. Please help me!
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

Kelly drove north for 12 miles and then east for 9 miles

Applying the Pythagorean Theorem to find the distance for the 'straight road'

 sqrt(144 + 81) = sqrt(225) = 15mi, length of straight road

 D = r*t OR t = D/r

t%5BK%5D+=+21%2F42+=+.5hr     |Took Kelly 30 min

t%5BB%5D+=+15%2F45+=+%281%2F3%29hr  |Took Brenda 20 min

How many minutes earlier than Kelly did Brenda arrive? 10min