How much does a 13-year-old’s brain weigh?
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500gm
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900gm
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1.4kg
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1kg
Reveal answer
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Correct answer
Explanation
The human brain reaches approximately 90-95% of its adult size by age 6, and by age 13 it weighs about 1.3-1.4 kg, which is very close to the adult brain weight. The brain doesn't grow significantly in size after early childhood - development is mostly in connectivity and myelination.
AI explanation
By around age 13, the human brain has essentially reached its adult size and weight, roughly 1.4 kilograms, since most brain growth in mass occurs in early childhood. This is why the figure matches the commonly cited adult brain weight rather than a smaller value like 900 grams, which is closer to an infant's brain weight.