Difference between revisions of "1950 AHSME Problems/Problem 27"
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==Solution== | ==Solution== | ||
| − | The car takes <math>120 \text{ miles }\cdot\dfrac{1 \text{ hr }}{30 \text{ miles }}=4 \text{ hr}</math> to get from <math>A</math> to <math>B</math>. Also, it takes <math>120 \text{ miles }\cdot\dfrac{1 \text{ hr }}{40 \text{ miles }}=3 \text{ hr}</math> to get from <math>B</math> to <math>A</math>. Therefore, the average speed is <math>\dfrac{240\text{ miles }}{7 \text{ hr}}=34\dfrac{2}{7}\text{ mph}</math>, which is closest to <math>\textbf{(B)}\ 34\text{ mph}</math>. | + | The car takes <math>120 \text{ miles }\cdot\dfrac{1 \text{ hr }}{30 \text{ miles }}=4 \text{ hr}</math> to get from <math>A</math> to <math>B</math>. Also, it takes <math>120 \text{ miles }\cdot\dfrac{1 \text{ hr }}{40 \text{ miles }}=3 \text{ hr}</math> to get from <math>B</math> to <math>A</math>. Therefore, the average speed is <math>\dfrac{240\text{ miles }}{7 \text{ hr}}=34\dfrac{2}{7}\text{ mph}</math>, which is closest to <math>\boxed{\textbf{(B)}\ 34\text{ mph}}</math>. |
==See Also== | ==See Also== | ||
Latest revision as of 14:49, 14 February 2016
Problem
A car travels 
miles from 
to 
at 
miles per hour but returns the same distance at 
miles per hour. The average speed for the round trip is closest to:
Solution
The car takes 
to get from to . Also, it takes 
to get from to . Therefore, the average speed is 
, which is closest to 
.
See Also
| 1950 AHSC (Problems • Answer Key • Resources) | ||
| Preceded by Problem 26 |
Followed by Problem 28 | |
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| All AHSME Problems and Solutions | ||
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. 
