Looking for some statistics help

[Iconoclastic]

1. If I want to find out what % of the local population (say, 10 million total people) consider themselves to be music lovers, how many people do I need to poll before I can achieve, say 95% confidence level with, say a confidence interval of +-2.5% (for example 30-35%)? Or +-5% (for example 30-40%)?

2. Similarly, if I want to ask X number of people in the local population what THEY think the true % of the local population is who consider themselves to be music lovers, how many people would I need to ask before I can achieve 95% confidence level that the mean answer I get from that X number of people is +-2.5 or +-5% of the true mean (the mean that I would have had I asked every single person in the local population)?

Anything would be appreciated.

[KPucks]

As long as it is a simple random sample, you would really only need 30 respondents before the data becomes approximately normally distributed about the mean. However, the moe people you can get the better. Just remember, the sample must be random or your results mean nothing.