Medical College Admission Test (MCAT) Practice Exam

To determine the percentage change represented by a 5-pound difference for a person weighing 200 pounds, the just noticeable difference concept can be applied. The just noticeable difference (JND) is often expressed as a proportion, where the change is divided by the original amount and then multiplied by 100 to convert to a percentage.

In this case, the calculation is performed as follows:

1. Take the change in weight, which is 5 lbs.

2. Divide that change by the original weight of the person, which is 200 lbs. This gives us 5 / 200 = 0.025.

3. Multiply by 100 to convert this decimal into a percentage: 0.025 * 100 = 2.5%.

This indicates that a change of 5 lbs represents 2.5% of the total weight of a 200 lbs person.

The choice indicating this calculation is the most accurate representation of the just noticeable difference concept applied to this scenario. The percentage increase of 2.5% reflects the threshold of change that is noticeable, aligning perfectly with the conditions set forth by the question.