单选题
Andrew fitted an electric toy car with hard rubber wheels that had deep treads and placed the car on a smooth, flat surface. Andrew started the car and a stopwatch at the same time. Andrew stopped the stopwatch as the car crossed the 75-foot mark. He calculated the results of 3 separate trials as shown in the table below./r/n /r/n
/r/n Andrew repeated the procedure, except he fitted the car with soft rubber wheels that were smooth and lacked treads. The results are shown in the table below./r/n /r/n /r/n
| Procedure 1 | |
| Trial Number | /r/nTime in seconds |
| 1 | /r/n22.8 |
| 2 | /r/n23.2 |
| 3 | /r/n22.5 |
| Procedure 2 | |
| Trial Number | /r/nTime in seconds |
| 1 | /r/n57.0 |
| 2 | /r/n56.2 |
| 3 | /r/n56.9 |
单选题
What was the average time the car with the soft wheels took to cross the 75-foot mark?
【正确答案】
D
【答案解析】The soft wheels data is in the second table. Calculate the average of those three times: (57.0 + 56.4 + 56.7) ÷ 3 = 56.7
单选题
Assuming that the car traveled at a constant speed, approximately how far had the car with hard wheels traveled in Trial 3 after 11.25 seconds?
【正确答案】
B
【答案解析】Since the car traveled at a constant speed, you can set up a proportion between the time and distance of the whole run and the time and distance of the partial run.
[*]
Therefore, the car traveled 37.5 feet in 11.25 seconds.
[*]
Therefore, the car traveled 37.5 feet in 11.25 seconds.
单选题
During which procedure and trial did the car travel at the highest speed?
【正确答案】
C
【答案解析】The data in the tables reflects the amount of time the cars took to travel a constant distance. Therefore, the car that finished in the least amount of time traveled at the highest speed.
单选题
Assuming the car in Procedure 1 traveled at a constant speed, approximately how long would it take the car to travel 100 feet?
【正确答案】
C
【答案解析】The first step is to calculate the average speed for all three trials: (22.8+23.2+22.5)÷3=22.8. Next, since the car traveled at a constant speed, you can set up a proportion between the time and distance of the whole run and the time and distance of the partial run: 22.8÷75=0.304 sec/feet. Finally, multiply 0.304 by 100 to get 30.4 seconds.