Question

Researchers measured the muscle mass of 16 women (grams per cubic centimeter). The table below shows the results, paired with the age of each woman. The first 15 data pairs are plotted below ABe Muscle 71 Muscle 82 140 120 100 91 78 67 56 73 68 56 68 87 73 78 40 76 65 45 58 45 43 100 49 105 84 116 76 97 AGE 53 100 1. Which is the explanatory variable? 2. Add the point corresponding to muscle age 53 and muscle mass 100 to the scatterplot above. Circle the point corresponding to age 68 and muscle mass 78. 3. The association between age and muscle mass is fairly strong. The direction is The form is 4. Compute the correlation coefficient r.

Answer 1

1) EXPLANATORY VARIABLE IS AN  INDEPENDENT VARIABLE WHICH IS HERE AGE.

2)

MUSCLE 140 120 116 ◆ 105 100 ◆ 91 ◆ 87 84 80 76 ◆ 73 ◆ 68 65 MUSCLE 60 40 20 10 20 30 40 50 60 70 80 90

3) THE DIRECTION IS DOWNWARD.

THE FORM IS NEGATIVE CORRELATION.

4) By using excel function CORREL we have

r = -0.82389