You interview 100 people about who their favorite rock band is. Of those 100, 80 replied that their favorite band is Aerosmith. The 80 that replied claimed they listened to music 75 minutes each day, with a standard deviation of 10 minutes.
a.) Construct a 99 Confidence Interval for the mean time per day spent listening to music for those who actually replied.
b.) What sample size is necessary to make a 95% CI for those who replied? The margin of error should be 0.1.