A95% confidence interval for a population mean μ is given as (18.7, 21.3). this confidence interval is based on a simple random sample of 48 observations. calculate the sample mean and sample standard deviation. assume that all conditions necessary for inference are satisfied. use the excel function t. inv as necessary to obtain values from the t-distribution in any calculations and give all answers to 3 decimal places.

Mrs. julien’s and mrs. castillejo’s classes are selling cookie dough for a school fundraiser. customers can buy packages of macadamia nut chip cookie dough and packages of triple chocolate cookie dough. mrs. julien’s class sold 25 packages of macadamia nut chip cookie dough and 30 packages of triple chocolate cookie dough for a total of $221.25. mrs. castillejo’s class sold 5 packages of macadamia nut chip cookie dough and 45 packages of triple chocolate cookie dough for a total of $191.25. (a) write the system of equations that model the problem. be sure to explain which equation represents which situation. (b) find the cost of each type of cookie. show your work. (c) explain which method you used to solve the system and why you chose that method.