GMAT Practice Question: Jonah drove the first half of a 100 -mile trip in x hours and the second half in y...
Question
Jonah drove the first half of a 100 -mile trip in x hours and the second half in y hours. Which of the following is equal to Jonah's average speed, in miles per hour, for the entire trip?
- \frac{50}{x+y}
- \frac{100}{x+y}
- \frac{25}{x}+\frac{25}{y}
- \frac{50}{x}+\frac{50}{y}
- \frac{100}{x}+\frac{100}{y}
Topics: word problems, rates, translations, units
Solution
Step 1
We translate \textbf{\text{"a 100-mile trip"}} into an equation for the total distance.
\text{Total distance} = 100
Step 2
We translate \textbf{\text{"in x hours and y hours"}} into an equation for the total time.
\text{Total time} = x + y
Step 3
We use the distance formula to find average speed by dividing total distance by total time.
\text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{100}{x+y}
Answer
\frac{100}{x+y}
