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Computer keypad failure can be attributed to electrical defects or mechanical defects. A repair facility currently has 25 failed keyboards, 6 of which electrical have defects and 19 have mechanical defects. a. In how many ways can a sample of 5 keyboards be selected so that exactly two have an electrical defect? (10 pts) b. A sample of 5 keyboards are selected. What is the probability that at least 4 of these will have mechanical defects? (10 pts)