Using the BOYHGTS data file, complete the following:

A. Assume you were randomly sampling this population of boys and you drew three samples, the first sample was 10 individuals (starting on line 423 and ending on line 432, do NOT use observation #423-432), the second sample was 20 (423 through 442), and the last was 50 (423 through 472), calculate 95% confidence intervals. How did the confidence intervals change as sample size increased?

n = 10: Mean: ___ Standard Deviation: ___t: ___CL lower: ___ CL upper: ___
n = 20: Mean: ___ Standard Deviation: ___t: ___CL lower: ___ CL upper: ___
n = 50: Mean: ___ Standard Deviation: ___t: ___CL lower: ___ CL upper: ___

B. From a national survey we know that the average height for this age group is 60 inches with a standard deviation of 2 inches. Is the null hypothesis accepted or rejected for the above samples?
H₀: height is equal to 60 (a two tail test) 
H₁: height is not equal to 60
n = 10: Accept or reject null hypothesis
n = 20: Accept or reject null hypothesis
n = 50: Accept or reject null hypothesis

C. Calculate the z - scores for the three samples, compare the z score to the t-statistic, is the null hypothesis accepted or rejected?

z-score                                                     t-stat

N = 10: _______ _______ Accept or reject null hypothesis
N = 20: _______ _______ Accept or reject null hypothesis
N = 50: _______ _______ Accept or reject null hypothesis

D. Assume we want a measurement error (ME) of 0.5 inches, how large of a sample will be needed using the standard deviation from the n = 50 sample for your calculation?

n: ______