To determine which object had the fastest average speed over the five trials, we first need to calculate the average time taken by each object over the trials. Then we'll calculate the average speed using the formula:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]
where the distance is 100 centimeters.
1. 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: \[ \text{Average time} = \frac{1.8 + 1.9 + 2.1 + 1.7 + 1.5}{5} = \frac{9.0}{5} = 1.8 \text{ seconds} \]
2. Calculating Average Speed:
Now we calculate the average speed for each object:
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Toy: \[ \text{Speed} = \frac{100 \text{ cm}}{3.0 \text{ s}} = 33.33 \text{ cm/s} \]
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Block: \[ \text{Speed} = \frac{100 \text{ cm}}{3.3 \text{ s}} \approx 30.30 \text{ cm/s} \]
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Ball: \[ \text{Speed} = \frac{100 \text{ cm}}{2.16 \text{ s}} \approx 46.30 \text{ cm/s} \]
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Pen: \[ \text{Speed} = \frac{100 \text{ cm}}{1.8 \text{ s}} \approx 55.56 \text{ cm/s} \]
Conclusion:
The object with the fastest average speed is the Pen, with an average speed of approximately 55.56 cm/s. Therefore, the answer is:
the Pen