I need answer from a-c

(1 point) A surgery has a success rate of 75%. Suppose that the surgery is performed on three patients. a. What is the probability that the surgery is successful on at least 2 patients? 84 % b. On average, how many surgeries can.we expect to be successful if performed on a group of three patients? 2.1 c. What is the standard deviation of the number of successful surgeries performed on a group of three patients? 0. . Your answers must be accurate to the nearest hundreth