SOLUTION: Luke hiked up a 41/2-mile trail to the top of Mt. Washington at an average speed of 21/7 mph. His dad hiked the same trail at an average speed of 21/4 mph. If Luke’s dad reaches

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Question 1139149: Luke hiked up a 41/2-mile trail to the top of Mt. Washington at an average speed of 21/7 mph. His dad hiked the same trail at an average speed of 21/4 mph. If Luke’s dad reaches the top of the mountain at noon, at what time will Luke arrive?
Found 3 solutions by Boreal, josgarithmetic, ikleyn:
Answer by Boreal(15235) About Me  (Show Source):
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4.5=9/2
9/2 divided by 15/7, which is 2 1/7 is 9/2*7/15=63/30 or 2.1 hours
9/2 divided by 9/4, which is 2 1/4 is 9/2*4/9=2 hours
Luke arrives 0.1 hour later or 6 minutes after noon.

Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
              SPEED            TIME           DISTANCE

Luke          21%2F7=3                           4%261%2F2

Dad           21%2F4=5%261%2F4                         4%261%2F2

Time quantities easily filled in, T=D%2FR. 
              SPEED            TIME           DISTANCE

Luke          21%2F7=3         1%261%2F2                4%261%2F2

Dad           21%2F4=5%261%2F4       6%2F7               4%261%2F2

The extra time Luke needed compared to his dad, 1%261%2F2-6%2F7=9%2F14hours. If dad reached top at noon, then Luke reached top 9%2F14 hours later, or 0.64286 hour, or 39 minutes.

Answer by ikleyn(52775) About Me  (Show Source):
You can put this solution on YOUR website!
.

In the future, when you post to this forum, NEVER write 41/2,


since different people will read and interpret it DIFFERENTLY.


One will interpret as  41%2F2;  the other will read  41%2F2.


Write 4 1/2 in this case, using the "blank" symbol between the integer part and the fraction.