Question

20 pts] In a survey of 400 likely voters, 215 responded that they would vote for the incumbent and 185 responded that they would vote for the challenger. Let p denote the fraction of all likely voters who preferred the incumbent at the time of the survey, and let p be the fraction of survey respondents who preferred the incumbent.

Answer 1

g)

h)

for 99 % CI value of z=				2.576
margin of error E=z*std error                            =				0.064
lower confidence bound=sample proportion-margin of error				0.474
Upper confidence bound=sample proportion+margin of error				0.602

i)

for part h we require higher confidence and to copensate for higher confidence critical values are higher for distribtuion as more areas in the tail is included ; therefore interval in part h is wider

j)as 95% Confidence interval contains 0.5 as plausible value for population proportion ; therefore we can not reject null hypothesis