Q. The arithmetic mean of the following numbers 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6 and 7, 7, 7, 7, 7, 7, 7 is :
Answer: 5
Notes: Required Mean of this given series = $latex = \frac{1\times 1+2\times 2+3\times 3+4\times 4+5\times 5+6\times 6+7\times 7}{1+2+3+4+5+6+7}&s=2$ $latex = \frac{1+4+9+16+25+36+49}{28}&s=2$ $latex =\frac{140}{28} = 5&s=1$ Hence option [B] is correct answer.

2