A teacher gives her students the following test problem:
Box A, which is sliding to the right on a frictionless horizontal surface, collides with box B which is initially at rest.  The two boxes stick together after the collision and continue sliding as a single unit.  Find the final speed of the combined boxes.
However, rather than giving the students the necessary information, the teacher is making them purchase the information according to the following price list.
The change in the kinetic energy of box B as a result of the collision    Rs. 50
The change in the momentum of box B as a result of the collision        Rs. 80
The average force acting on box B during the collision                         Rs. 70
The time t, that the two boxes are in contact during the collision           Rs. 90
The mass of box B                                                                                 Rs. 40
What is the least amount of money that must be spent in order to purchase enough information to solve the problem?