The velocity of the ball is thrown into the air is  ft/s.

The function of the ball is .

(a)

Average velocity :

The average velocity is defined as the ratio of change in distance by change in time.

, where .

Now ball is at beginning stage at .

Substitute in the function .

(i)

Find the average velocity at .

Substitute and in the above expression.

The average velocity at is  ft/s.

(ii)

Find the average velocity at .

Substitute and in the above expression.

The average velocity at is  ft/s.

(iii)

Find the average velocity at .

Substitute and in the above expression.

The average velocity at is  ft/s.

(iv)

Find the average velocity at .

Substitute and in the above expression.

The average velocity at is  ft/s.

(b)

Find the instantaneous velocity when .

Instantaneous velocity :

The instantaneous velocity is defined as .

Substitute in the above expression.

               ( Since )

The instantaneous velocity when is  ft/s.

(a) (i) The average velocity at is ft/s.

     (ii) The average velocity at is ft/s.

     (iii) The average velocity at is ft/s.

     (iv) The average velocity at is ft/s.

(b) The instantaneous velocity when is ft/s.