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G. A professor studied a sample of 112 students and found a positive association between Students' study effort (X) and their grades (Y). She decides to introduce a control variable, Student's IQ (Z), and obtained the following first-order table: (6 pts) Student's IQ level (2) Low High Study effort (X) Study effort (X) Grades (Y) Low High All Low High All Low 16 12 28 19 7 26 High 10 16 26 9 23 32 Total 26 28 54 28 30 5B 1. Use an appropriate measure of association to calculate the strength and direction for each one of these two partial tables. 2. Construct a zero-order table between Study effort (X) as independent and Grades (Y) as dependent. Use an appropriate measure of association to explain the strength and direction of the association between X and Y. 3. Compare the zero-order association to the first-order partial associations and determine the type of relationship that exists between X and Y, and the type of control variable Z is