The quality control of an electronic device requires the examination of its performance experimentally using five temperature settings, three humidity levels, and six vibration conditions. How many tests are necessary to perform the quality-control testing of a device under all the combinations of conditions? Assume now that we have two devices. The examination in this case starts with the first device to limit the testing of the second device only to the conditions of temperature, humidity and/

or vibration that have a significant effect on performance. For example, if temperature was found to have insignificant effect on performance based on testing the first device, the second device is tested only for humidity and vibration while keeping temperature at the same level. Construct a probability tree to represent all the possible testing scenarios.