STATS Sanders BRCC Questions and Answers

Normal Distribution Graph - P(x) - probability of x x̅ - x bar / mean X - your variable # You need to obtain new desks for an incoming class of 25 kindergarten students who are all 5 years of age. An important characteristic of the desks is that they must accommodate the sitting heights of those students. (The sitting heights is the height of a seated student from the bottom of the feet to the top of the knee.) The table below lists the parameters for sitting heights of 5 year olds. in cm Boys Girls Population mean (mu) 61.8 61.2 Population standard deviation (sigma) 2.9 3.1 Distribution Norm Norm a. What sitting height will accommodate 95% of the boys? b. What sitting height is greater than 95% of the means of sitting heights from a random sample of 25 boys? - mu= 61.8 cm sigma = 2.9 cm x= sitting height P(x) = .95 a) x= mu + (z * sigma) x= 61.8 + (1.645 * 2.9) x= 66.6 cm x bar = ? n = 25 K students z= x bar - mu / sigma sub x bar b) sigma sub x bar = sigma/ sqrt of n2.9/ sqrt 25 = 2.9/5 = .58 z (1.645) = x bar - 61.8/ .58 1.645 * .58 =x bar -61.8 .9541 = x bar -61.8 .9541 + 61.8 =x bar 62.8 cm = x bar z - z score z = ((x-̅ μ)/(σsubx̅)) - converting sample means to z score