Dr G is planning to do a research to figure out the average time per week students spend time in his Statistic course. He is going to use a 90% confidence Interval and he wants the mean to be within ‡ 4 hours. Assuming the time spent by his students is Normally distributed with a sample standard deviation of 600 minutes. The sample size he needs to choose should be closest to:
482
31
247
17
