Please help, very confused.

ANSWERING THE FOLLOWING

#1)A study was made by a retail merchant to determine the relationship between #weekly advertising expenditures and sales. The following data were recorded: ad.cost <- c(40, 20, 25, 20, 30, 50, 40, 20, 50, 40, 25, 50) sales <- c(385, 400, 395, 365, 475, 440, 490, 420, 560, 525, 480, 510)

#a) Plot a scatter plot

#b) Find the 90% interval of the range of the mean of sales when #ad expenditures is $35 (About $430.089 to $482.779)

#c) Determine the 90% interval of the potential range of values for the sales #when the ad expenditures is $35 (from about 361.666 to 551.202)

#d) Determine the 90% interval of the potential range of values for the sales #when the ad expenditures is $40 (from about 376.887 to 568.189)