Question

Nine subjects, 87 to 96 years old, were given 8 weeks of progressive resistance weight training. strength before and after training for each individual was measured as maximum weight (in kilograms) lifted by left knee extension:

Answer 1

Answer:

11.611 +/- 3.013

Explanation:

3     3.5     4       6        7          8        8.5        12.5       15

7      17      19      12       19       22       28         20         28

difference

4      13.5    15     6       12        14        19.5        7.5         13

mean = 11.611

the standard deviation ⇒ 7.611² + 1.889² + 3.389² + 5.611² + 0.389² + 2.389² - 7.889² + 4.111² + 1.389² = 57.927 + 3.568 + 11.485 + 31.483 + 0.151 + 5.707 + 62.236 + 16.9 + 1.929 = 191.386/9 = √21.265 = 4.611

standard deviation = 4.611  1.918

confidence interval = mean +/- [(standard deviation/√9) x 1.96]

11.611 + [(4.611/3) x 1.96] = 11.611 + 3.013

11.611 - [(4.611/3) x 1.96] = 11.611 - 3.013