I need the answer for this question. please provide me the R codes if you use R. i need the full answer for this question. thank you

An advertising firm is concerned about the effect of a new regional promotional cam- paign on the total dollar sales for a particular product. A simple random sample of n = 20 stores is drawn from the / = 452 regional stores in which the product is sold. Quarterly sales data are obtained for the current three-month period and the three-month period prior to the new campaign (see the accompanying table). Store Precampaign sales Presnet sales Store Precampaign sales Presnet sales 208 239 11 599 626 400 428 12 510 538 440 472 13 828 888 259 276 14 473 510 351 363 15 924 998 880 942 16 110 171 273 294 17 829 889 487 514 18 257 265 183 195 19 388 419 863 897 20 244 257 (a) Using the scatterplot to decide whether the ratio estimator is appropriate. (b) Use these data to estimate Ty, the total sales for the current period, and place a bound on the error of estimation. Assume T, = 216, 256. (c) To estimate the mean sales / for the current period within in a bound on the estimation error = = 5, how many more stores we need to sample