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Brain weight $\"\"$ as a function of body weight $\"\"$ in fish is $\"\"$ , where $\"\"$ and $\"\"$ are measure in grams.

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Body weight as a function of body length $\"\"$ is $\"\"$ .

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Average length of a certain species of fish evolved from $\"\"$ cm to $\"\"$ cm at a constant rate over $\"\"$ million years.

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Find the rate of change of length.

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$\"\"$

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Consider $\"\"$ .

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Differentiate on each side with respect to $\"\"$ .

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$\"\"$

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Substitute $\"\"$ in above expression.

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$\"\"$

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Consider $\"\"$ .

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Differentiate on each side with respect to $\"\"$ .

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$\"\"$

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Substitute $\"\"$ and $\"\"$ in above expression. $\"\"$

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Find the rate at which species brain growing when average length is $\"\"$ cm.

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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Rate at which species brain growing when average length was $\"\"$ cm is $\"\"$ grams/million year.

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Rate at which species brain growing when average length was $\"\"$ cm is $\"\"$ grams/million year.