A researcher conducted a mail survey of the students of University X to determine what percentage of these students were interested in purchasing a combined season ticket for basketball and football. She mailed out questionnaires to a simple random sample of 500 students. 80 students responded to the mail survey. 40 out of these 80 students were interested in purchasing the combined ticket. The researcher then randomly selected 120 students out of the 420 students who did not respond to the mail survey, and contacted them by telephone. All of these 120 students cooperated. 30 out these 120 students were interested in purchasing the combined ticket. Let It denote the proportion of students at University X who were interested in purchasing the combined basketball and football season ticket. Construct a 99% confidence interval for T. (Show work)