The Heights of 9-Year-Old Children Are Normally Distributed, with a Mean

The heights of 9-year-old children are normally distributed, with a mean of 123 cm and a standard deviation of 10 cm.
a. Find the probability that one randomly selected 9-year-old child is taller than 125 cm.
b. Find the probability that three randomly selected 9-year-old children are taller than 125 cm.
c. Find the probability that the mean height of three randomly selected 9-year-old children is greater than 125 cm.