You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: if the sides of a triangle are 20 cm , 12 cm and 16 cm , what is its area ? 
Options: a ) 70 , b ) 79 , c ) 85 , d ) 96 , e ) 92
Solution: d
Why? "Based on the pythagorean theorem, the triangle with sides 20 cm, 12 cm and 16 cm is right angled, where the hypotenuse is 20 cm. area of the triangle = 1 / 2 * 12 * 16 = 96 cm 2 answer : option d"

New input: Problem: a certain cube floating in a bucket of water has between 80 and 90 percent of its volume below the surface of the water . if between 6 and 13 cubic centimeters of the cube ' s volume is above the surface of the water , then the length of a side of the cube is approximately 
Options: a ) 4 , b ) 5 , c ) 7 , d ) 8 , e ) 9
Solution:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
a