standard_description: Understand that two events A and B are independent if the probability of A and B occurring together is the product of their probabilities, and use this characterization to determine if they are independent.
problem_activity: Task
About how many cells are in the human body?
You can assume that a cell is a sphere with radius 10$^{-3}$cm and that the density of a cell is approximately the density of water which is 1g/cm$^3$.


aligns: no