To find out how long the cheetah was running, we can use the formula:
\[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \]
In this case, the distance is 75 meters, and the speed is 25 meters per second.
Calculating the time:
\[ \text{Time} = \frac{75 \text{ meters}}{25 \text{ meters/second}} = 3 \text{ seconds} \]
Therefore, the cheetah was running for 3 seconds.