Could you help with this please??

If a ball is thrown straight up into the air with an initial velocity of 70 ft/s, it height in feet after t second is given by y = 70t - 16t. Find the average velocity for the time period begining when t = 1 and lasting (i) 0.1 seconds (ii) 0.01 seconds (iii) 0.001 seconds Finally based on the above results, guess what the instantaneous velocity of the ball is when t = 1