30. A truck driver drove 225 miles at an average speed of 50 miles per hour and another 210 miles at an average speed of 60 miles per hour. What was the total driving time?
Answer: D
The total driving time was 8 hours.
The truck driver spent a total of 8 hours driving, which includes the time taken for each segment of the journey at their respective average speeds.
A) 6 hours 30 minutes
This option is incorrect because the calculated driving times for both segments exceed this duration. The first segment at 50 mph takes 4.5 hours, and the second segment at 60 mph takes 3.5 hours, totaling 8 hours.
B) 7 hours
This option is also incorrect as it underestimates the total driving time. The sum of the individual segment times, 4.5 hours and 3.5 hours, clearly adds up to 8 hours, which is more than 7 hours.
C) 7 hours 30 minutes
This choice is incorrect as well. Although it is closer to the total, it still does not account for the combined driving time of 8 hours calculated from both driving segments.
D) 8 hours
This is the correct answer since the total driving time is derived from the calculations: 225 miles at 50 mph takes 4.5 hours, and 210 miles at 60 mph takes 3.5 hours, resulting in a total of 8 hours.
Conclusion
The correct answer of 8 hours accurately reflects the total time taken for the entire journey when calculated correctly from both segments. All other options fail to account for the actual driving times, which clearly exceed their respective durations, confirming that D is definitively the right answer.