ANSWER

8 - 11 year olds

a-- In the square that measures 5 squares on each side,

The robot will not reach the exit at once because there are 10 steps and 10 is even.

In two tries it can. Any pair of odd numbers that adds up to 10 works:

1 step and 9 steps, 3 and 7, 5 and 5, 7 and 3, 9 and 1.

In three tries the robot will never reach the exit because the sum of three odd numbers is odd and the robot will never get 10 steps.

b-- If the square measures 6 squares on each side,

The robot cannot exit at once because there are 12 steps and 12 is even.

T In two tries it can. Any pair of odd numbers that adds up to 12 works:

1 step and 11 steps, 3 and 9, 5 and 7, 7 and 5, 9 and 3, 11 and 1.

In three tries the robot will never reach the exit because the sum of three odd numbers is odd and the robot will never get 12 steps.