# The Harris Poll asked a sample of 1009 adults which causes of death they thought would become more common in the future. Gun violence topped the list: 706 members of the sample thought deaths from guns would increase. ?

##
(a) how to explain what the population proportion p is for this poll ?

(b) How to find a 95% confidence interval for p ?

(c) Harris announced a margin of error of plus or minus three percentage points for this poll result. Is there any effect on answer (b) ?

(d) If the confidence level is 90%, what is the difference between 95% and 90% confidence level ?

(a) how to explain what the population proportion p is for this poll ?

(b) How to find a 95% confidence interval for p ?

(c) Harris announced a margin of error of plus or minus three percentage points for this poll result. Is there any effect on answer (b) ?

(d) If the confidence level is 90%, what is the difference between 95% and 90% confidence level ?

##### 1 Answer

Answers bellow

#### Explanation:

a) the population proportion cannot be determined as that represents everyone. The sample, however, allows us to determine a point estimate,

The Point estimate is,

or in this case

b) to determine a confidence interval we use the equation,

where z is the z-score for your confidence level and

For a 95% confidence z= 1.959963985

so subbing into,

c) not sure exactly what you mean.

was think of using this equation but I'm not sure what you want to find out.

d) a smaller confidence interval 95%

A 95% confidence interval means that 95% of sample means taken will lie within this range. A 90% confidence interval means that 90% will lie within its range, which is smaller. For example,

95%

90%

The 90% confidence interval is smaller and thus we are less confident that the actual population mean lies within its range.