A study of organ damage was done on hypertensive patients seen at a clinic. The following table was compiled from 306 newly identified cases of hypertension and shows evidence of end organ damage classified by severity of hypertension.

Two new patients with hypertension come to the clinic on the same day. What is the probability that both have abnormal electrocardiogram?

Severity of Hypertension Mild to moderate Severe All History of Angina Positive 18 7 25 Negative 243 38 281 All 261 45 306 History of Stroke Positive 4 1 5 Negative 257 44 301 All 261 45 306 Electrocardiographic Positive 56 22 78 abnormality Negative 205 23 228 All 261 45 306