A cliff has been eroded into an arch in the shape of a parabola. The height y of the arch, in metres, above the water at high tide can be modelled by the function y = -2.5x2 - 30x - 67.5, where x is the horizontal distance in metres from the cliff's edge. a. Determine the maximum height of the arch. X2 -6. y = 22.5 b. Determine the width of the arch where it meets the water. c. State the appropriate domain and range. 4. The revenue for sales of a stuffed toy at a carnival is modelled by the quadratic function y = (48 - 4x) (5 + 0.5x). The current price is $5, and x represents the number of $0.50 price increases. How many $0.50 price increases will maximize revenue? onus 5. A road tunnel in the shape of a parabola has a maximum height of 9m. The tunnel's width at its base is 12m. a. Determine the equation of a quadratic function that could model this situation. b. What is the maximum clearance at a distance of 1m from the edge of the tunnel