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Daily Magic Spell : May 9th

 
 
LiuAnna的头像
Daily Magic Spell : May 9th
LiuAnna 发表于 2017年05月9日 Tuesday 13:29
 

David blew his tire and had to drive with a temporary replacement tire for a while. He was not supposed to use that tire to drive long distances or to drive fast, but still he drove to work one day. His average speed going to work was 35 miles per hour and took him about 50 minutes to get there. On his way back home he took a different route; he was going on average at 45 miles per hour and it took him about 45 minutes to complete the trip. How many miles did David drive with this temporary tire? Round your answer to the nearest mile.

45

4

 I answered 63 and I got it incorrect. This was the explanation:

On the way to work it took him 50/60= 5/6 hours to get there, so he traveled  5/6 x 35 = 29.16 miles. On the way back it took him 45/60 = 3/4 of an hour, so he traveled 3/4 x 45 = 33.75 miles. Thus, David traveled 29.16 + 33.75 = 66.91, which is approximately 67 miles.



29.16 + 33.75 = 62.91, which is about 63 miles, so I think I got it correct.

 
ReynosoDavid的头像
Re: Daily Magic Spell : May 9th
ReynosoDavid 发表于 2017年05月10日 Wednesday 12:35
 

Hello Anna, 

You are correct. There was a typo in the solution of the problem. The correct answer is 62.91, which rounds up to 63. If you go back to the problem you'll see that you have now the 5 points for having the correct answer in the first try. 

Thank you for letting us know! 

David