To find which ratio is smaller, we can first turn each of these ratios into fractions and then see which fraction is greater. 4:2 is equal to 4/2 which is equal to 2. 5:4 is equal to 5/4 which is equal to 1
which is further equal to 1.25. Looking at 2 and 1.25, we can tell that 1.25 is smaller because the units digit (2 and 1 respectively) is smaller in 1. That means that the smaller ratio is 5:4.