 So our next problem, we're going to look at the length of rabbit ears. So the question says, suppose that the length of rabbit ears is dictated by polygenetic inheritance. Remember, polygenetic inheritance is where you have multiple alleles that are going to add together to create the overall phenotype. There are four alleles that code for this trait. All the dominant alleles, which are capital L, add five centimeters of length. All of the recessive alleles, which are lower case L, only add two centimeters of length. So if the P generation consists of a homozygous dominant and a homozygous recessive parent, predict the probability that the offspring will have at least 25 centimeter long ears. So the P generation, if it's all homozygous dominant, that means that we have eight alleles of dominant length. We also have a homozygous recessive that has eight alleles of recessive length. When we cross these two generations together, we get an F1 generation that is heterozygous and length. Heterozygous and length. But we're not done. We want to know the F2 generation and we want to know that it will have 25 centimeter long ears. In order to have at least 25 centimeter long ears, we know that we have to have at least five dominant alleles. So we are looking for five capital letters, which is equal to dominant alleles. So what we're going to do is we're going to run a binomial expansion. For our binomial expansion is a plus b to some power, to some power. This power we're going to find, remember four alleles, two copies of each, four times two is eight. So our binomial expansion is a plus b to the eighth power. Now I'm going to spare you the binomial expansion working all of it all out. I'm going to let you guys figure this out and work it out on your scratch paper. However your end result is listed for you here. Remember that the number that's in front of your particular variable tells you how many of that offspring will have that particular trait. A stands for your capital letters or dominant traits. B is for your lower case. So you have eight capitals, seven, so on and so forth. We're looking for five. Five capitals, which gives you at least a length of 25 centimeters. So when we look at this, we have 56 of your possible 256 combinations. We'll have at least 25 centimeter long ears, which means that there is a 21.88 chance that this will happen. So using binomial expansion and understanding what the letters and numbers stand for really helps you crack this genetic code fairly quickly.