One sample intervals for means

Dr. Suarez, a veterinarian, would like to create a $99\%$ confidence interval for the average number of calories a chihuahua typically eats in a day. A pilot study suggests that the daily caloric intake of chihuahuas has a standard deviation of $30$ calories. **Determine the smallest size random sample of chihuahuas that Dr. Suarez should select in order to ensure a margin of error of no more than $8$ calories.** [[☃ radio 1]]