Mathematics (AS & A Level) · May / June 2017 · Paper 72 · Question 3
9709
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Household incomes, in thousands of dollars, in a certain country are represented by the random variable X with mean - and standard deviation 3. The incomes of a random sample of 400 households are found and the results are summarised below. n = 400 Σ x = 923 Σx2 = 3170 2
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3(i)[3]
3(ii)[5]
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