Your colleague proposes to test the mechanism of ant navigation by placing a food source 7 m from the nest. she will then pick up the ants from the nest and move them 4 meters from the nest (3 m from the food source). based on the previous data, when do you expect the ants to start searching for their nest on their return trip

immediately

Explanation:

The ants move independently to search food from the nest, but at the same time they go away from the nest, they leave a way of pheromones, this is their mechanisms to return to the nest.

In average, the ants could take like 100 or 200 meters from the nest to search food, so 7 meters is a very small distance, and with the way of pheromones, they will return to their nest easily.

not sure if this is what you'r looking for nnew= nold