The weight of children in the U.S. are normally distributed with a mean of 8.0 pounds and standard deviation of 1

The weight of children in the U.S. are normally distributed with a mean of 8.0 pounds and standard deviation of 1 pound. A random sample of 100 children results in a sample mean of 7.7 pounds. What is the probability of a single randomly selected child having a weight that is less than or equal to 7.7 pounds?