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Maths Puzzle
The mean of 19 observaton is 24. If the mean of the first 10 observations is 17 and that of the last 10 observations is 24,find the 10th observation.
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- 1st + 2nd + ----- + 19th =24 x 19 = 456 (eq 1)
1st + 2nd + --- + 10th = 170 (eq 2)
10th + 11th + ---- +19th = 240 (eq 3)
eq 1 - eq 2
11th + 12th + ----- +19th = 456-170=286 (eq 4)
eq 3 - eq 4
10th= -46
ans = -46 - 11 years agoHelpfull: Yes(9) No(0)
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