2019 AMC 8 Problems/Problem 16
Problem 16
Qiang drives miles at an average speed of
miles per hour. How many additional miles will he have to drive at
miles per hour to average
miles per hour for the entire trip?
Solution 1(answer options)
The only option that is easily divisible by is
. Which gives 2 hours of travel. And by the formula
And = $\frac{\text{Total Distance}}{{\text{Total Time}}$ (Error compiling LaTeX. Unknown error_msg)
Thus
Both are equal and thus our answer is
~phoenixfire
Solution 2
Note that the average speed is simply the total distance over the total time. Let the number of additional miles he has to drive be Therefore, the total distance is
and the total time (in hours) is
We can set up the following equation:
Simplifying the equation, we get
Solving the equation yields
so our answer is
.
~twinemma
See Also
2019 AMC 8 (Problems • Answer Key • Resources) | ||
Preceded by Problem 15 |
Followed by Problem 17 | |
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