Question

a car has the velocity of 2.35 after 4.67 it's velocity is 9.89 what is the average acceleration

Answer 1

Average acceleration  =  (change in speed) / (time for the change) .
  
Change in speed = (ending speed) - (beginning speed)

                       =  (9.89 miles/hour) - (2.35 yards/second)  = 26,839.2 ft/hr

Acceleration  =  (26,839.2 ft/hr) / (4.67 days)  =  2,873.58 inch/hour²