You are given two true-breeding groups of guinea pigs. The guinea pigs in the first group have brown coat color and long tails; the guinea pigs in the second group have a white coat color and short tails. When you produce an F generation, by crossing these two groups, you see only guinea pigs with brown coat color and long. tails. When you produce an F2 generation, by crossing F's together, you see some guinea pigs with brown coat color (75%) and some guinea pigs with white coat color (25%). You also see some of the guinea pigs have short tails (25%) and others (75%) have long tails. If the single alleles responsible for coat color and tail appearance sort independently, what percentage of the brown guinea pigs are expected to have long tails?