Denny studied the effect of postural change on cardiovascular reactivity in a sample of healthy men and women. Change in systolic blood pressure (SBP) from supine to standing position was used as the measure of cardiac reactivity in a sample of 842 adults. Supine measurement of blood pressure was taken after participants had lain on an examination table for 15 minutes. Blood pressure was measured every 20 seconds using a Dynamap device for 2 minutes, and the six measurements were averaged. Participants then stood up, and an additional six measurements were made for another 2 minutes. Below is a table describing the characteristics of Denny's sample.

Question: If age were normally distributed, approximately what percent of the sample would be younger than 50?