Question

1. A polling organization talks to several people concerning what is their preferred method of obtaining political news.

	18-30	31 - 55	56 and over
Printed Publication	12	25	33	70
Television	5	27	40	72
Internet Sources	58	29	22	109
	75	81	95	251

The table breaks the information by age.

a. [3] What proportion of respondents

preferred where age 31 to 55 or preferred to get political news via internet sources?

b. [3] Of the respondents that preferred to get political news via printed publication what percentage where 56 and over?

c. [3] Show that the events a person is 18 to 30, a person prefers to get political news via television are not independent events.

Answer 1

1)

a)

P(preferred where age 31 to 55 or preferred to get political news via internet sources)

= P(preferred where age 31 to 55) + P(preferred to get political news via internet sources) - P(preferred where age 31 to 55 and preferred to get political news via internet sources)

i.e. 64.14%

b)

Now, n(respondents that preferred to get political news via printed publication) = 70

n(respondents that preferred to get political news via printed publication and are 56 and over) = 33

Required percentage = %

c)

For two events to be independent, we should have

Now, P(person is 18 to 30 and prefers to get political news via television are not independent events) =

P(person is 18 to 30) =

P(prefers to get political news via television are not independent events) =

Now, since, P(person is 18 to 30 and prefers to get political news via television are not independent events) P(person is 18 to 30) . P(prefers to get political news via television are not independent events)

So, the two events are not independent.