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: Option B

According to the question,
Average = $$\frac{1+2+2+3+3+3+4+4+4+4+5+5+5+5+5+6+6+6+6+6+6+7+7+7+7+7+7+7}{28}$$
Average = $$\frac{1+2\times 2+3\times 3+4\times 4+5\times 5+6\times 6+7\times 7}{28}$$
Average = $$\frac{1+4+9+16+25+36+49}{28}$$
Average = 5