Each of 11 refrigerators of a certain type has been returned to a distributor because of an audible, high-pitched, oscillating noise when the refrigerators are running. suppose that 7 of these refrigerators have a defective compressor and the other 4 have less serious problems. if the refrigerators are examined in random order, let x be the number among the first 6 examined that have a defective compressor. (a) calculate p(x = 4) and p(x ≤ 4). (round your answers to four decimal places.) p(x = 4) = p(x ≤ 4) = (b) determine the probability that x exceeds its mean value by more than 1 standard deviation. (round your answer to four decimal places.) (c) consider a large shipment of 400 refrigerators, of which 40 have defective compressors. if x is the number among 25 randomly selected refrigerators that have defective compressors, describe a less tedious way to calculate (at least approximately) p(x ≤ 5) than to use the hypergeometric pmf. we can approximate the hypergeometric distribution with the distribution if the population size and the number of successes are large. here n = and p = m/n = . approximate p(x ≤ 5) using that method. (round your answer to three decimal places.)