1. What percentage of people falls between -2 and +2 standard deviations on IQ scores ( if the general population of IQ scores assumes a normal distribution )?
2. The following is a sample of responses to a survey asking teens how many cigarette they had smoked in the last 30 days. Please calculated S2 ( variance ) and S ( standard deviation ) and report the middle 68% and the 95% of the cigarette smoking behavior. 1, 0, 0 , 2, 0, 3, 0, 2, 0, 4, 0, 1, 1, 1, 5, 5, 5, 20, 20