Amarketing student is estimating the average amount of money that students at a large university spent on sporting events last year. he asks a random sample of 50 students at one of the university football games how much they spent on sporting events last year. using this data he computes a 90% confidence interval, which turns out to be ($217, $677). which one of the following conclusions is valid? a. we can be 90% confident that the mean amount of money spent at sporting events last year by all the students at this university is between $217 and $677. b. 90% of the sample said they spent between $217 and $677 at sporting events last year. c. no conclusion can be drawn.