Average speed is calculated as the total distance traveled divided by the total time taken.
Given:
\[
\text{Distance}_1 = 25 \, \text{m}, \quad \text{Time}_1 = 5 \, \text{s}
\]
\[
\text{Distance}_2 = 25 \, \text{m}, \quad \text{Time}_2 = 3 \, \text{s}
\]
1. Total Distance:
\[
25 \, \text{m} + 25 \, \text{m} = 50 \, \text{m}
\]
2. Total Time:
\[
5 \, \text{s} + 3 \, \text{s} = 8 \, \text{s}
\]
3. Average Speed:
\[
\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} = \frac{50 \, \text{m}}{8 \, \text{s}} = 6.25 \, \text{m/s}
\]
Final Answer
\[
\boxed{6.25 \, \text{m/s}}
\]