Suppose a random sample of 137 households in a city was selected to determine the average annual household spending on food at home for city residents. The sample results are contained in the accompanying table. Complete parts a and b below. Click the icon to view the City Eats data. a. Using the sample standard deviation as an estimate for the population standard deviation, calculate the sample size required to estimate the true population mean to within 130 with 90% confidence. How many additional samples must be taken? The required sample size is|]. (Round up to the nearest whole number.) The number of additional samples required is(]. (Type a whole number.) b. Using the sample standard deviation as an estimate for the population standard deviation, calculate the sample size required to estimate the true population mean to within 1 30 with 98% confidence. How many additional samples must be taken? The required sample size is. (Round up to the nearest whole number.) The number of additional samples required is| (Type a whole number.)