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The mean of 12, 22, 32, 42, 52, 62, 72 is -
Answer & Solution
Correct Answer:
Option
B
12 + 22 + 32 + . . . . . + n2 = $$\frac{{n\left( {n + 1} \right)\left( {2n + 1} \right)}}{6}$$
∴ 12 + 22 + 32 + . . . . . + 72 = $$\left( {\frac{{7 \times 8 \times 15}}{6}} \right)$$ = 140
So, required average
$$ = \left( {\frac{{140}}{7}} \right)$$
= 20
∴ 12 + 22 + 32 + . . . . . + 72 = $$\left( {\frac{{7 \times 8 \times 15}}{6}} \right)$$ = 140
So, required average
$$ = \left( {\frac{{140}}{7}} \right)$$
= 20
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