I found a confidence interval of (13500-8180,13500+8180) for part a, but how should i find the probability that revenue is larger than spending?

PollIUS oral, o pis each A study was performed of the results of online ad campaigns. The study followed 30 different ad campaigns. The businesses purchasing the ads spent an average of $20,000, with an SD of $5,000. The results of the study estimated that the average campaign produced $30,000 in revenue, and that each additional $1,000 of spending resulted in an additional $1,500 of revenue to the company. The residual standard error from the study was $4,000 a) Your company plans to spend $27,000 on an advertising campaign. Calculate a 95% confidence interval for the net profit you'll get (spending - revenue): b) What is the probability that your ad campaign will be profitable - that is, that revenue will exceed spending