Let x be a random variable that represents white blood cell count per cubic milliliter of whole blood. Assume that x has a distributi that is approximately normal, with mean = 7,600 and estimated standard deviation = 1,700. A test result of x < 3,500 is an indication of leukopenia. This indicates bone marrow depression that may be the result of a viral infection. USE SALT (a) What is the probability that, on a single test, x is less than 3,500? (Round your answer to four decimal places.) (b) Suppose a doctor uses the average x for two tests taken about a week apart. What can we say about the probability distribution of x? The probability distribution of x is approximately normal with x=7600 and = 850. The probability distribution of x is not normal. The probability distribution of x is approximately normal with = 7600 and The probability distribution of x is approximately normal with = 7600 and What is the probability of x < 3,500? (Round your answer to four decimal places.) = 1700. = 1202.0815. (c) Repeat part (b) for n = 3 tests taken a week apart. (Round your answer to four decimal places.)