Question

Find the standard deviation of the sample. 2, 3, 5, 6, 9, 12, 13, 16, 19, 20

a. 7.081 b. 5.359 c. 5.812 d. 6.287 e. 6.519

Answer 1

steps for standard deviation-

1. work out the mean.

2. then for each number, subtract the mean and squarethe results

3. then work out the mean of those squared results.

4. take the square root of that and we are done.

1.mean = (2+3+5+6+9+12+13+16+!9+20)/10 = 10.5

2. (2-10.5)(2-10.5) = 72.25

(3-10.5)(3-10.5) = 56.25

(5-10.5)(5-10.5) = 30.25

similarly for other numbers

3. mean of the numbers calculated in step 2-

72.25+56.25+30.25+20.25+2.25+2.25+6.25+30.25+72.25+90.25 = 382.5

382.5/10 = 38.25

4. square root of 38.25 = 6.185