Question

A CBS News poll conducted June 10 and 11, 2006, among a nationwide random sample of 651 adults, asked those adults about their party affiliation (Democrat, Republican or none) and their opinion of how the US economy was changing ("getting better," "getting worse" or "about the same"). The results are shown in the table below.

	better	same	worse
Republican	38	104	44
Democrat	12	87	137
none	21	90	118

Express each of your answers as a percent rounded to the nearest tenth (for example, 12.3%).

1. What percent of survey respondents identified themselves as affiliated with neither party (marginal probability)?
2. What percent of survey respondents thought the economy was about the same and were affiliated with neither party (joint probability)?
3. What percent of those affiliated with neither party thought the economy was about the same (conditional probability)?

Answer 1

	Better	Same	Worse	Total
Republican	38	104	44	186
Democrat	12	87	137	236
None	21	90	118	229
Total	71	281	299	651

Consider the above table:

a) it can be observed from the table that 229 people affiated themselves with neither party.

so, % of survey respondant under this category is given by: (229/651)*100=35.2%

b) no of respondent who thought that economy was about the same and were affliated with neither party is 90.

% of respondent who are affliated with neither party and thought that economy was about the same is given as: (90/651)8100=13.8%

c) no of people who thought that economy was about the same among the people that supported neither party is=90

% people who are affliated with neither party thought that economy was about the same is (90/229)*100=39.3%