Below is data for 250 offspring mice, as produced in a laboratory. A 5-column table has 4 rows. The first column has entries Predicted fraction, predicted percentage, simulated fraction, simulated percentage. The second column is labeled Black fur and black eyes with entries 9/16, 56.25 percent, 155/250, 62 percent. The third column is labeled Black Fur and Red Eyes with entries 3/16, 18.75 percent, 51/250, 20.4 percent. The fourth column is labeled White Fur and Black eyes with entries 3/16, 18.75 percent, 44/250, 17.6 percent. The fifth column is labeled White fur and red eyes with entries 1/16, 6.25 percent, 20/250, 8 percent.

Notice that the predicted percentages and laboratory percentages are not the same. These differences most likely result from