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Question
Hi Scott

It takes Sarah 45 minutes to drive to work everyday. If the distance travelled from her house to her workplace is 64.5km, calculate the average speed she drives (answer to nearest 1km/h)

Thanks

Answer
To find the speed, just divide distance by time.
This would give 64.5 km /45 min, which is 43 km /30 min.
That works out to be near 1.4333 km / min.

This is not the answer, though, for the answer needs to be in the nearest km/h.
Since there are 60 min/hr, take 60 (min/hr) * 43 km / 30 min to get 86 km/hr.

Note that since by visual inspection, 45 minutes is 3/4 of an hour.
To multiply 64.5 by 4/3, it can be seen that 20 is roughly 1/3 of 64.5,
so we should get something a little bigger that 64.5 + 20, which (roughly) is around 85.

Since we got 86, which is only one more, that must be right.  

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Scott A Wilson

Expertise

I have answered every question that was a story problems that had any relation to math for which an answer existed. I have ever answered some questions which had a vague relation to math, but still related.

Experience

My experience is from when I started doing story problems in grade school. I have been assisting, helping, and bringing smiles to many others ever since. Are you the next one?

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In over 850 questions answered to other users. Maybe you're the next one ...

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I received a BA in Mathematical Sciences from OSU and a MS in Mathematics from OSU as well.

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I earned Both my BS degree and MS degree with honors for having such a high grade point average.

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I have answered hundreds and hundreds of students at OSU in the 80's and over 8,500 questions right here, but only a little over 850 of them have been word problems.

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