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Use a two-tailed test with α = .01 to test whether the intervention had a significant impact on mental health symptoms.

Consider the following birth control effectiveness chart.        

Wow! Those numbers are staggering! Moreover, with an average person consuming roughly 126.4 grams of sugar per day, the U.S. leads the world in sugar consumption. This is unfortunate because too much sugar can cause heart disease, diabetes and obesity.   Anyway, let’s get back to calculations…

What proportion of youth consume more than 16 teaspoons of sugar a day? Please do not round proportions. Report the exact value as you see it in the Unit Normal Table.  [color1]

Looking at the graph, which sample means might be significantly different, and which are not? Please explain how you know.

For random samples of n = [value calculated in Q14] selected from the given population, what is the range of values that is expected for the sample mean 99% of the time?

What proportion of men consume between 20 and 24 teaspoons of sugar? Please do not round proportions. Report the exact values as you see them in the Unit Normal Table. 

Consider the following statistics. Sugar Consumption Stats.pdf

Calculate the average number of mental health symptoms after the intervention. Report the exact value without rounding.  

A researcher recruited a sample of adolescents who devote 8 or more hours per day to screens and encouraged them to visit friends and family instead of spending time online. The number of their mental health symptoms after the intervention are presented below.