This is because using a punnet square reveals that each option has a dominant allele of large ears, leaving no room for the recessive trait of small ears.
What percent of potassium-40 remains undecayed in a rock that is 3.9 billion years old? The 3.9 billion year old rock has undergone three half-lives (3.9 divided by 1.3 = 3). After 3 half-lives, 12.5% of the potassium-40 remains undecayed.
