The toll to a bridge is 2.50. A three-month pass costs $12.00 and reduces the toll to $0.50. A six month pass $37 and permits crossing the bridge for no additional fee. How many crossing per three month period does it take for the three month pass to be the best deal.

Find the volume of the described solid.the solid lies between planes perpendicular to the x-axis at x = 0 and x=7. the cross sectionsperpendicular to the x-axis between these planes are squares whose bases run from the parabolay=-31x to the parabola y = 30/x.a) 441b) 147c) 864d) 882