Group B: Solve only one; 25p each. B.1) Let the random variable X represent the number of cars that are used for official business purposes on any given workday. The probability distribution for...

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Extracted text: Group B: Solve only one; 25p each. B.1) Let the random variable X represent the number of cars that are used for official business purposes on any given workday. The probability distribution for company A is 2 3 PA(X) 0.4 0.4 02 and for company B is 1 2 3 4 PB(X) 0.1 0.1 0.4 0.3 0.1 If daily records of car usage are examined on randomly selected 36 days from company A and 40 days from company B, find the probability that the difference between sample means of company A and B is greater than 0.5.