Explanation:

To understand why the IQ will be 100 when the mental age and chronological age are the same, we need to first understand the concept of IQ and how it is calculated.

What is IQ?

IQ stands for Intelligence Quotient, which is a measure of a person's cognitive abilities and intellectual potential. It is a standardized test that provides an estimate of a person's intelligence level compared to the general population.

How is IQ calculated?

IQ is calculated using the following formula:

IQ = (Mental Age / Chronological Age) * 100

Here, mental age refers to the level of cognitive functioning or intellectual ability that an individual demonstrates, while chronological age refers to the actual age of the individual.

When mental age and chronological age are the same:

When the mental age and chronological age are the same, it means that the individual's intellectual ability is in line with their actual age. In other words, the individual is performing at an average level compared to others in their age group.

Why is the IQ 100 in this case?

According to the IQ formula, when the mental age and chronological age are the same, the ratio of mental age to chronological age is 1. Therefore, the IQ is calculated as (1/1) * 100, which equals 100.

An IQ of 100 is considered average and is the midpoint of the IQ scale. It indicates that the individual's intellectual abilities are on par with the average population. For example, if a 10-year-old child has a mental age of 10, their IQ would be 100, suggesting that they are performing at an average level for their age.

Conclusion:

When the mental age and chronological age are the same, the IQ is calculated as 100. This indicates that the individual's intellectual abilities are average compared to others in their age group.