Let A= Patient suffering from heart ailment and B= Set of patient suffering from lungs infection Given, n(A)=89% and n(B)=98% n(A∪B)≥n(A)+n(B)−n(A∩B) ⇒100≥89+98−n(A∩B) ⇒87≤n(A∩B) Also, n(A∩B)=min{n(A),n(B)} ⇒n(A∩B)≤89 ∴87≤n(A∩B)≤89 So, n(A∩B)∉{79,81,83,85}.