Question

what is the average time for the toy car to move 1.0 m on dirt?
○ 20.2 s
○ 24.4 s
○ 28.1 s
○ 60.7 s

time for toy car to travel 1.0 m on different surfaces

surface	time (s) trial 1	time (s) trial 2	time (s) trial 3
tile	29.1	26.7	28.5
cement	25.5	23.4	24.2

Explanation:

Step1: Recall the formula for average

The formula for the average (mean) of a set of values is the sum of the values divided by the number of values. For the dirt surface, we have three trial times: \( t_1 = 20.0 \, \text{s} \), \( t_2 = 19.2 \, \text{s} \), and \( t_3 = 21.5 \, \text{s} \). The number of trials \( n = 3 \).

Step2: Calculate the sum of the times

First, we find the sum of the three times. So, \( \text{Sum} = t_1 + t_2 + t_3 = 20.0 + 19.2 + 21.5 \). Let's calculate that: \( 20.0+19.2 = 39.2 \), and then \( 39.2 + 21.5 = 60.7 \, \text{s} \).

Step3: Calculate the average

Now, we divide the sum by the number of trials to get the average. The average \( \bar{t} = \frac{\text{Sum}}{n} = \frac{60.7}{3} \). Let's compute that: \( \frac{60.7}{3} \approx 20.2 \, \text{s} \) (when rounded to one decimal place).

Answer:

20.2 s