Question

(If you could include the work so I can teach myself it would be appreciated)

EMC research conducted a poll between Jan. 14 and Jan 22 2014. They asked a SRS of 805 voters to see if they supported the minimum raise hike to $15/hr. They found a sample proportion of 68%. Find a confidence interval for the true proportion of voters that suppose the minimum raise hike to $15/hr with a 90% confidence level.

a. Parameter (2pts):

b. Conditions (2pts):

c. Calculation (4pts):

d. Conclusion (2pts):

Answer 1

a) The parameter here is the population proportion of voters who supported the minimum raise hike to $15/hr.

b) The conditions here given is we are to find a confidence interval of 90% confidence. From standard normal tables, we have:
P( -1.645 < Z < 1.645) = 0.9

Therefore 1.645 is the critical value here.

c) The calculations here are done as:

This is the required confidence interval here.

d) The conclusion here is that as the whole confidence interval lies above 0.5, the majority of voters under 90% confidence supports the minimum raise hike to $15/hr.