The step 3 exercise tells us that a hybrid male individual and a hybrid female individual (F1) mate with each other and have offspring. In this context, by the term hybrid, we know that the exercise refers to the organisms' genotype having two different alleles for the fur color (in this case we can use B for black fur color, and b for white, for example), what would be Bb. We can complete then the Punnet squares as follows:
Here we can see the information that will be useful to do the other square, which is like the following:
We can compare these two probabilities by saying that for 3 organisms with black fur, there would be 1 with white fur, having a ratio of 3:1. This also can be approached by saying that the predicted percentage usually reflects the simulated numbers and the simulated percentages, since although there can be a lower or higher ratio, it is still near that value: 3:1.