Answer:
10.6 s
Step-by-step explanation:
First of all, let's convert both speeds into m/s:
- Cheetah:

- Gazelle:

Taking as reference the position x = 0, the position of the cheetah at time t is

while the position of the gazelle, which starts 68.8 m ahead, is

The cheetah catches the gazelle when the two positions are equal:

and substituting the speeds and solving for t, we find the time at which the cheetah reaches the gazelle:
