i have 4 boxes labeled A to D, and 10 rocks.

i put 1 rock in A, 2 in B, 3 in C and 4 in D.

A[⚪] B[⚪⚪] C[⚪⚪⚪] D[⚪⚪⚪⚪]

i then paint 1 rock in B, 2 rocks in C and 1 rock in D.

A[⚪] B[⚪🔴] C[⚪🔴🔴] D[⚪⚪⚪🔴]

then i put the boxes in a bigger box called the united boxes.

here’s the rate of painted rocks:

1. C 66% (2/3)
2. B 50% (1/2)
3. United boxes 40% (4/10)
4. D 25% (1/4)
5. A 0% (0/1)