4. (a) In an opinion poll of 1800 people, 1242 said that they preferred red wine to white wine. Calculate a 95\% confidence interval for the proportion of people in the population who prefer red wine to white wine.
(b) In another opinion poll of 1000 people on the same subject, the following confidence interval was calculated.
[0pt]
[0.672, 0.732].
Determine
- the number of people in the sample who stated that they prefer red wine to white wine,
- the confidence level of the confidence interval, giving your answer as a percentage correct to three significant figures.