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Question 1 of 20 This question: 1 point(s) possible Submit test A projectile is fired vertically upward into the air; its position (in feet) above the ground after t seconds is given by the function s(t) shown below. Use limits to determine the instantaneous velocity of the projectile at t = a seconds for the given value of a. s(t) = - 1612 + 84t; a = 2 The instantaneous velocity at t = 2 is ft / s 2. ft/s