An air compressor, weighing 1000 lbs., and operating at 1500 rpm, is to be mounted on a suitable isolator to prevent unwanted vibration to the floor. A helical spring with stiffness of 45,000 lb/in., another helical spring with stiffness of 15,000 lb/in, and a shock absorber with a damping ratio of 0.15 are available for use. Design the isolation system to provide the best possible isolation using a combination of the springs and dampers provided.