Due to an outbreak of strep at a college, all 100 students in a dormitory will be tested for strep infection. Ten of these students actually have strep. The test identifies strep in 90% of those where strep is present, and correctly returns a negative result in 80% of cases where strep is not present.

1)How many students will be expected to have a positive test result?

2)What is the positive predictive value, i.e., what percent of those who test positive actually have strep?

3)What is the conditional probability of having no strep infection given the negative test result?