Question

Your organization has recently started advertising its services on the internet. The marketing manager has indicated that she wants to know how long it takes internet users to access your company’s internet screen, since there is concern it is taking too long and deterring interest. You have asked colleagues and friends at a variety of other
organizations to access your company’s website and keep a careful record of how long it took them to get into the company’s home page. The results for 120 attempts are:

Access time (seconds)	No. of attempts at success (frequency)
11 -      15 16   -     20 21    -    25   26    -     30       31    -     35 36     -    40	15 26 18 29 20 12

a)

Complete the table below.

Access time	frequency (f)	Midpoint (x)	(f) * (x)	Cummulative Frequency (x)	(f)*X2
11   -   15	15
16   -   20	26
21   -   25	18
26    - 30	29
31   -   35	20
36    - 40	12

Based on the completed table in question 1, answer the following questions.
b) Calculate the mean.  

c) Calculate the Standard Deviation

d) What is the class width

Answer 1

Solution:

d)

Class Width = (x - y) / n

= 40 -11 /6 = 4.83