GRE General TestQuantitative ReasoningMedium
A satellite orbits Earth at a constant speed. If it completes 5 full orbits in 12.5 hours, how many minutes does it take to complete 3 full orbits?
- A450
- B150
- C750
- D300
Show answer & explanationAnswer & explanation
Correct answer: A. 450
First, find the time taken for one orbit in hours. Then, multiply this by 3 to find the time for 3 orbits. Finally, convert the total hours to minutes.
Why the other options are wrong
- B. This is incorrect; likely a miscalculation in converting units or in the initial division.
- C. This is incorrect; possibly the time for 5 orbits in minutes, not 3, or other error.
- D. This results from calculating 2 orbits, or a direct multiplication error.
Unit Rate and Conversion
Calculating a rate per single unit of quantity, then using that rate to determine a total for a different quantity, often involving unit conversions.
- Unit rate = Total Quantity / Total Units.
- Conversion factor for hours to minutes is 60 minutes/hour.
- Ensure all calculations are performed with consistent units or convert at the appropriate step.
Memory trick: Rate First, Then Convert: Find the rate per unit, then scale and change units.