normalcdf help

#1
For my homework I have some problems idk how to do.

Example question:
The mean for a test is 110, with a standard deviation of 15.
Find the probability that a collection of 4 people get an average score between 90 and 120.

I know you have to use the normalcdf function on the calculator but I can't figure out what order to input the #'s in. any ideas?