Question

1. The following data represent the travel time (in minutes) to school for seven students enrolled in Chaffey College. Treat the seven students as a sample.  

Student	Travel time
John	32
Jeff	24
Kevin	15
Ron	40
Noel	32
Mary	23
Christy	27

(a) Find standard deviation of the sample. (b) Find variance of the sample.                                                                                                                

Answer 1

Solution :

We are given a data of sample size n = 7

32,24,15,40,32,23,27

Using this, first we find sample mean() and sample standard deviation(s).

T

T
=   
sumof observations n

= (32 + 24.......+ 27)/7

= 27.571

T

Now ,

s =   

ΣΕ (Χ, - X)2 η – 1

s = $\sqrt{}$(32 - 27.571)² + ... + (27 - 27.571)²/ 7 - 1

s = $\sqrt{}$385.714/6

s = 8.018

Sample standard deviation s = 8.018

The sample variance s² ,

s² = 8.018² = 64.286

The sample variance s² =  64.286