Question

A study of blood pressure (BP) is done on 100 healthy individuals aged 25-27 years. The result is a normal distribution with median BP of 120 mm Hg. What percentage of the subjects will have a BP reading higher than 120?

• A. 25
• B. 50
• C. 75
• D. 100

Hint:

In a normal distribution, mean = median = mode, and the curve splits exactly 50-50 about that centre value.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
We are told the BP readings of 100 healthy people follow a normal distribution, and the median value is 120 mm Hg. We need to find what share of readings sit above 120.

Step 2: Key Concept:
A normal distribution is a symmetric, bell-shaped curve. In a perfectly symmetric curve, the mean, median, and mode all sit at the same point, right at the centre of the bell.

Step 3: Detailed Explanation:
Because the curve is symmetric about its centre, exactly half the area under the curve lies to the left of that centre point and exactly half lies to the right.
Here the centre point is the median, 120 mm Hg.
So half of the 100 subjects, meaning 50 subjects, will have a BP reading below 120, and the other half will have a reading above 120.
The reading of exactly 120 mm Hg sits at the centre itself and is not counted as higher than 120.

Step 4: Final Answer:
50 percent of the subjects will have a BP reading higher than 120 mm Hg, so option (B) is correct.