Refer to the data file P08_66.xdsx: Comfy Company sells mediumpriced patio furniture through a mail-order catalog. It has operated primarily in the East but. is now expanding to the Southwest. To get off to a good start, it plans to send potential customers a catalog with a discount coupon. However, Comfy is not sure how large a discount is needed to entice customers to buy. It experiments by sending catalogs to selected residents in six eties. Tucson and San Diego receive coupons for 5% off any furniture within the next two months, Phoenix and Santa fe receive coupons for 10% off, and Riverside and Albuquerque receive coupons for 15% otf. Comfy wonders whether there are differences across pairs of cities that receive the same discount. a. Caiculate a 95% contidence interval for the difference between the mean amount spent for the following pairs of cities: (These means should include the "0 purchases." Round your answers to one decimal place, if necessary. If your answer is negative number, enter "minus" sign.) b. Cakculate a 95% confidence interval for the difference between the proportion of customers who purchase something for the following pairs of cities: (Round your answers to three decimal places, if necessary. If your answer is negative mumber, enter "minus" sign.) Refer to the data file P08_66.xdsx: Comfy Company sells mediumpriced patio furniture through a mail-order catalog. It has operated primarily in the East but. is now expanding to the Southwest. To get off to a good start, it plans to send potential customers a catalog with a discount coupon. However, Comfy is not sure how large a discount is needed to entice customers to buy. It experiments by sending catalogs to selected residents in six eties. Tucson and San Diego receive coupons for 5% off any furniture within the next two months, Phoenix and Santa fe receive coupons for 10% off, and Riverside and Albuquerque receive coupons for 15% otf. Comfy wonders whether there are differences across pairs of cities that receive the same discount. a. Caiculate a 95% contidence interval for the difference between the mean amount spent for the following pairs of cities: (These means should include the "0 purchases." Round your answers to one decimal place, if necessary. If your answer is negative number, enter "minus" sign.) b. Cakculate a 95% confidence interval for the difference between the proportion of customers who purchase something for the following pairs of cities: (Round your answers to three decimal places, if necessary. If your answer is negative mumber, enter "minus" sign.)