Air Raid Inc. designed 20 air-conditioning systems designed for use by astronauts in the International Space Station. All of them were operated for 1,000 hours at NASA's test facility. Out of all the systems 2 of them failed during the test. One of them after 200 hours and the other after 600 hours. What is the Percentage Failure Rate? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a 5% b 10% c 15% d 20% e 25%