Text: The prevalence of disease is 0.2% or 2 per 1000. Therefore, in 100,000 screened people, there will be 200 who are diseased. Since the test has 85% sensitivity, the screening test will be positiive in 0.85 x 200 = 170 people.

Therefore, among the 200 diseased people, there will be 200-170 =30 who are diseased but have a negative screening test.