Answer:
The smallest possible length is 0.83m
Step-by-step explanation:
Given

Required
The smallest length of the tank
Since the tank is cubical, then the volume is:

This gives:

Express as 


Take cube roots of both sides

Rewrite as:

Approximate

12 this is because my number for sports is 12 and i just need to answer a ? for point thanks have a good day
If x is how long your friend swims and y is how long you swim, the answer would be x + 15 = y