Sorry this got to you super late. At least others looking for the answer can find it.
Answer:
1.92636657×10^-3
Step-by-step explanation:
This question looks quite awful coz it might be (16+81)^3/4 rather than being (16/81)^3/4....But, if it is (16/81)^3/4 the answer is 1.92636657×10^-3
hope you find it helpful....Thanks very much...
Divide 1681 by 4 which is about 420.25 feet for length