Question

Four students rode different buses to school, and each trip took 30 min.
One student rode 8 mi, one rode 10 mi, and the other two each rode 12 mi . What was the average speed of the buses? (1 point)

Answer 1

To calculate the average speed of the buses, we can use the formula for speed, which is:

\[
\text{speed} = \frac{\text{distance}}{\text{time}}
\]

Given that each trip took 30 minutes, we first need to convert that time into hours since speed is typically expressed in miles per hour (mph).

\[
30 \text{ minutes} = \frac{30}{60} \text{ hours} = 0.5 \text{ hours}
\]

Next, we can calculate the speed for each of the distances traveled by the four students:

1. For the student who rode 8 miles:
\[
\text{Speed} = \frac{8 \text{ miles}}{0.5 \text{ hours}} = 16 \text{ mph}
\]

2. For the student who rode 10 miles:
\[
\text{Speed} = \frac{10 \text{ miles}}{0.5 \text{ hours}} = 20 \text{ mph}
\]

3. For the first student who rode 12 miles:
\[
\text{Speed} = \frac{12 \text{ miles}}{0.5 \text{ hours}} = 24 \text{ mph}
\]

4. For the second student who rode 12 miles:
\[
\text{Speed} = \frac{12 \text{ miles}}{0.5 \text{ hours}} = 24 \text{ mph}
\]

Now we have the speeds for all four students:
- 16 mph
- 20 mph
- 24 mph
- 24 mph

To find the average speed of the buses, we can sum these speeds and then divide by the number of students:

\[
\text{Average Speed} = \frac{16 + 20 + 24 + 24}{4} = \frac{84}{4} = 21 \text{ mph}
\]

Thus, the average speed of the buses is **21 mph**.