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3. The mean price of a 3bedroom and 2bathroom house in the US suburban area is about $81,500 with a standard deviation of $6,400. If 45 such houses are for sale, the probability that the average price of these houses less than $80, 000 is (a) 0.4689 (b) 0.5311 (0) 0.3106 (d) 0.0579 (e) None of the above 4. A certain type of bacteria occurs in all raw milk. Let X denote the bacteria count per ml. of milk. The public health department has found that if the milk is not contaminated, then X has a distribution (probability histogram) that is more or less bellshaped and symmetric. The mean of the distribution of X is a = 2550 and the standard deviation 0 = 300. In a large commercial dairy, the health inspector takes 42 random samples of milk produced each day. At the end of the day the bacteria count in each of the 42 samples is averaged to obtain the sample average bacteria count Y. Assuming the mik is not contaminated, the probability that the sample average bacteria count f for one day is between 2400 and 2700 bacteria/ n11 is: (a) 0.12 % (b) 38.29 % (c) 56.32 % (d) 99.88 % (e) None of the above