Q.If \(∑f_i(x_i - a) = 400\), \(∑f_i = 50\), and \(a\) (assumed mean) = 52, then the value of the combined mean \(\bar{x}\) is – (a) 52 (b) 60 (c) 80 (d) 90
Answer: B
\(\bar{d} = \cfrac{∑f_i (x_i - a)}{∑f_i} = \cfrac{400}{50} = 8\)
∴ \(\bar{x} = a + \bar{d} = 52 + 8 = 60\)
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