A 0.9-kg block (mass m) and a second block (mass M) are both initially at rest on a frictionless inclined plane. Mass M rests against a spring that has a force constant of 12.2 kN/m. The distance d along the plane between the two blocks is 3.64 m. The 0.9-kg block is released, making an elastic collision with the larger block. The 1.00-kg block then rebounds a distance of 2.72 m back up the inclined plane. The block of mass M momentarily comes to rest 4.20 cm from its initial position. Find M.