4. Find the cost to produce 75 widgets if the initial cost is $2400 and C'(x) = 120 - 40x + x2. [Calculator] . /If a tennis ball is dropped from a height of 65 feet, on planet Euler takes 4 seconds to hit the ground, what is the gravity on the planet? A particle is moving along a line so that its velocity is v(t) = t3 - 9t2 + 15t + 10 feet per second at time t. [Calculator] A. What is the displacement of the particle on the time interval 0 S t s 5 ?