In Macomb County, body weights are normally distributed with a mean of 152 pounds

In Macomb County, body weights are normally distributed with a mean of 152 pounds and a standard deviation of 26 pounds. How many people must be surveyed if we want to estimate the percentage of Macomb County residents who weigh more than 180 pounds. Assume that we want 96% confidence that the error is no more than 4 percentage points.