To determine which object had the fastest average speed over the five trials, we need to calculate the average time it took for each object to travel 100 centimeters in each trial, and then use the formula for speed:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]
Since the distance is constant (100 cm), we can also express the average speed inversely proportional to the average time (a shorter time means a higher speed).
Let's calculate the average time for each object:
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Toy: \[ \text{Average Time} = \frac{3.1 + 2.9 + 3.0 + 2.9 + 3.1}{5} = \frac{15.0}{5} = 3.0 \text{ seconds} \]
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Block: \[ \text{Average Time} = \frac{3.2 + 3.0 + 3.6 + 3.3 + 3.4}{5} = \frac{16.5}{5} = 3.3 \text{ seconds} \]
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Ball: \[ \text{Average Time} = \frac{2.3 + 2.1 + 2.2 + 2.1 + 2.1}{5} = \frac{10.8}{5} = 2.16 \text{ seconds} \]
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Pen: \[ \text{Average Time} = \frac{1.8 + 1.9 + 2.1 + 1.7 + 1.5}{5} = \frac{9.0}{5} = 1.8 \text{ seconds} \]
Now that we have calculated the averages, we can compare them:
- Toy: 3.0 seconds
- Block: 3.3 seconds
- Ball: 2.16 seconds
- Pen: 1.8 seconds
The object with the fastest average speed, which corresponds to the shortest average time, is the Pen with an average time of 1.8 seconds.
Final Answer: the Pen