Question

10 babies are born in a hospital on the same day all weigh 2.8 KG each.what would be the standard deviation

Answer 1

$$Var={ \sum x^2 \over n} - \bar {x} ^2$$ $$SD = \sqrt {var}$$

n=10, x= 2.8

$$\sum x^2 = 10 * 2.8^2 = 78.4$$ $$\bar {x} = {\sum x \over n} = {10 * 2.8 \over 10} = 7.84$$

$${\sum x^2 \over n} = {78.4 \over 10} = 7.84$$

$$Var = 7.84 - 7.84 =0$$ $$SD =\sqrt {var} = \sqrt {0} =0$$

Answer: 0