Question

given the data: 15,11,9,10,10,3,12

find the standard deviation. The answer should be 4. something. Thanks

Answer 1

Solution:

Given that,

15,11,9,10,10,3,12

The mean of sample is   $\bar x$

$\sum$x/n =  (15 + 11 + 9 + 10 + 3+12 / 7)

   = 70/7

= 10

The sample mean is 10

Sample standard deviation is s

s = $\sqrt$1/(n-1)$\sum$(x - $\bar x$ )²

⁼  $\sqrt$1/6 (15 - 10 )²+ (11 - 10 )²+ (9 - 10 )²+ (10- 10 )² +( 10 - 10 )²⁺+( 3- 10 )²⁺+( 12 - 10 )²

= √13.333333333333

= 3.6515