George walks 1 mile to school. He leaves home at the same time each day, walks at a steady speed of 3 miles per hour, and arrives just as school begins. Today he was distracted by the pleasant weather and walked the first 12 mile at a speed of only 2 miles per hour. At how many miles per hour must George run the last 12 mile in order to arrive just as school begins today?

Question

Mathematics

Noodle

19 May, 16:27

George walks 1 mile to school. He leaves home at the same time each day, walks at a steady speed of 3 miles per hour, and arrives just as school begins. Today he was distracted by the pleasant weather and walked the first 12 mile at a speed of only 2 miles per hour. At how many miles per hour must George run the last 12 mile in order to arrive just as school begins today?

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Stephanie Norman · Answer 1

Note that on a normal day, it takes him 1/3 hour to get to school. However, today it took 1/2 mile 2 mph = 1/4 hour to walk the first 1/2 mile. That means that he has 1/3-1/4=1/12 hours left to get to school, and 1/2 mile left to go. Therefore, his speed must be 1/2 mile 1/12 hour = 6 mph, so 6 is the answer.