3. What is an expectation or expected value? (1 mark) 4. In the expansion of | x - - , find the general term. (2 marks) Part D: Application (9 marks) Show your work for FULL marks 1. It is found that a certain brand of light bulbs has a lifetime of 215 hours with a standard deviation of 12 hours. If the lifetime of the bulbs is assumed to be normally distributed, what percentage would you expect a. to fail in less than 200 hours? (2 marks) b. To have a lifetime of more than 250 hours? (2 marks)