Final answer:
The fish would weigh approximately 18.4 lb.
Step-by-step explanation:
To solve this problem, we can use the proportionality constant in the statement 'The weight of a fish varies jointly as its girth and the square of its length.' Let x be the weight of the fish we want to find.
According to the given information, we have the proportion:
24.5 lb / (35 in * (25 in)^2) = x / (30 in * (24 in)^2)
Simplifying, we get:
x = (24.5 lb * 30 in * (24 in)^2) / (35 in * (25 in)^2)
Calculating this expression, we get that the fish would weigh approximately 18.4 lb.