Answer :

Final answer:

The IQ of a 6-year-old child with a mental age of 9 is 150. This calculation is based on the formula for determining IQ, and places this child in a high IQ category often considered 'gifted'.

Explanation:

The IQ (Intelligence Quotient) is calculated by dividing the mental age by the chronological age and then multiplying by 100. In the case of a 6-year-old child with a mental age of 9, the calculation would be (9/6)*100, which equals 150. Therefore, the IQ of the child is 150 (option D).

It's important to note that this child would fall into a very high IQ category, as most people have an IQ between 85 and 115. Only approximately 2% of the population scores above 130, which is generally considered the threshold for being classified as 'gifted' within educational systems.

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