I need help with this problem on my review sheet for stats class. If you could do a step by step walk through I would appreciate it Thank you

8) A state's fish and game commission wants to estimate the mean number of fish caught this year during the fishing season. From previous surveys, it estimates that the standard deviation will be about 10. How many license holders will need to be surveyed if the commission wants the sample mean to be off from the true mean by at most 4 with 95% confidence? [7 pt]