There are two methods of teaching the skating technique in cross- country skiing. One-hundred fifty persons who finished last year's course, introduction to cross-country skiing, are available. Half will be taught by each method. After four one-hour lessons, each will be rated as satisfactory of not. The number of satisfactory ratings will be recorded.

(a) The goal is to compare the two methods. How would you randomize the subjects? Name one uncontrolled variable that could systematically effect the comparison if you don't ran- domize.

(b) The summary statistics are

Method 1 n₁ = 75 x = 62
Method 2 n₁ = 75 y = 47

Calculate a 98 % confidence interval for the difference in pro- portions that are satisfactory.

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The Answer of There are two methods of teaching the skating technique in cross- country skiing. One-hundred fifty persons who finished last year's course, introduction to cross-country skiing, are available. Half will be taught by each method. After four one-hour lessons, each will be rated as satisfactory of not. The number of satisfactory ratings will be recorded. (a) The goal is to compare the two methods. How would you randomize the subjects? Name one uncontrolled variable that could systematically effect the comparison if you don't ran- domize. (b) The summary statistics are Method 1 n₁ = 75 x = 62 Method 2 n₁ = 75 y = 47 Calculate a 98 % confidence interval for the difference in pro- portions that are satisfactory.

There Are Two Methods of Teaching the Skating Technique in Cross-