5 The day before the 1992 General Election, an opinion poll showed that \(37.6 \%\) of a random sample of 1731 voters intended to vote for the Conservative party.
- Calculate an approximate \(99.9 \%\) confidence interval for the proportion of voters intending to vote Conservative.
The actual proportion voting Conservative was above the upper limit of the confidence interval.
- Give two possible reasons for this occurrence.
- What sample size would be required to produce a \(99.9 \%\) confidence interval of width 0.05 ?