Work Step by Step
If the white cats died there would be only black cats, some BB and others Bb. Use the existing proportions: B=0.36+0.36+0.24 and b=0.24, the total of those numbers being 1.2. So, the frequency for B=0.96/1.2=0.8 and for b=0.24/1.2=0.2. Then, the proportion of white cats would be the freqency for b squared (that is, q^2), 0.2x0.2=0.04.