A new test- test B for Diabetes mellitus is performed in a group containing diabetics and non-diabetics.A standard test A has been used as reference to classify them as diabetics and non diabetics. If 120 mg/dl of blood sugar is taken as the cut-off for test B, the area shaded in the graph below represents -

Ans- The shaded area indicated has Diabetics proved by a standard test A with blood sugar levels less than 120 mg/dl. Which is less than the cut-off as per the test B criteria required to label them as Diabetic . Hence, even though the shaded area has diabetics - but not picked up by this particular test B- known as False Negative.