A food critic wishes to estimate the weights of premium steaks at a five star Texas style steakhouse. How large a sample must she select if she desires to be 90% confident that the true mean is within...

A food critic wishes to estimate the weights of premium steaks at a five star Texas style steakhouse. How large a sample must she select if she desires to be 90% confident that the true mean is within 6 ounces of the sample mean? The standard deviation of the steaks weights is known to be 8 ounces.