At the beginning of the school year, the 7th grade class at Oak Hill Middle School has 480 students. There are 270 girls and 210 boys.
part 1:
What is the probability that a randomly selected 7th grade student is a girl?
part 2:
Nineteen of the girls and 22 of the boys moved away, while 13 new girls and 20 new boys enrolled in the 7th grade at Oak Hill. After these changes in the class' composition, what is the probability that a randomly selected 7th grade student is a boy?