Question

Petroleum pollution in oceans stimulates the growth of certain bacteria. An assessment of this growth has been made by counting the bacteria in each of

5

randomly chosen specimens of ocean water (of a fixed size). The

5

counts obtained were as follows:

42, 56, 43, 45, 64

Find the standard deviation of this sample of numbers. Round your answer to two decimal places.

Answer 1

Solution:

Given that,

42,43,45,56,64

n = 5

The mean of sample is   

x/n =  (42 + 43 + 45 + 56 + 64 / 5)

   = 250 / 5

= 50

The sample mean is 50

Sample standard deviation is s

s = 1/(n-1)(x - )²

⁼  1/(5-1) (42 - 50 )²+ (43 - 50 )²+ (45 - 50 )²+ (56- 50 )² +( 64 - 50 )²

= 1/4 (64 + 49 + 25 + 36 + 196)

= 370/4

= 92.5

= 9.62

The sample standard deviation is = 9.62