Acceleration of the object is 8.75 m/s² and average velocity is 32.5 m/s
Explanation:
Acceleration of the object = Change in velocity/Time
                      = 50 - 15/4 = 35/4 = 8.75 m/s²
                   = 15 + 50/2 = 65/2 = 32.5 m/s