3. A researcher wants to find the weight of adult male sheep. A random sample of 37 adult male sheep indicated a standard deviation of the sheep weight to be 15.8 pounds. How many male sheep should be included in a sample to be 90% sure that the sample mean weight of all adult male sheep is within 2.5 pounds of the population mean weight? 4. A medical researcher wants to find the percentage of females who take vitamins. He wishes to be 95% confident the estimate is within 2% points of the true proportion. A recent study of 180 females showed that 25% took vitamins. How large should the sample size be