• Infant A was born premature and weighed 5 pounds at birth.

This is a linear growth problem involving rates. Let t represent the number of weeks. Infant A’s weight is represented by 5 + 4t, and Infant B’s weight is represented by 11 + 2t. Set the expressions equal to find when their weights match:

5 + 4t = 11 + 2t.

Subtract 2t from both sides:

5 + 2t = 11.

Subtract 5 from both sides:

2t = 6.

Divide by 2:

t = 3 weeks.

Therefore, option C is correct. NEX word problems often involve setting up equations from real-life healthcare scenarios, so identifying starting values and growth rates is essential.

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