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Question
Find x if 9, x, 14, 18 x, x, 8, 10 and 4 have a mean of 11.
Solution
Mean = `"Sum of observations"/"Total number of observations"`
⇒ 11 = `[ 9 + x + 14 + 18 + x + x + 8 + 10 + 4]/9`
⇒ 11 x 9 = 63 + 3x
⇒ 3x + 63 = 99
⇒ 3x = 99 - 63
⇒ 3x = 36
⇒ x = 12
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