Answer: The probability is 50%.
Step-by-step explanation: The probability that both are girls if the older child is a girl can be calculated through probability. First, we know that there are two genders the child can be, male or female. When we have 2 possible outcomes, the probability of each outcome is 50%. We know the first child is a girl, and that the second child has a 50% chance of being a girl, so the probability is 50%.