A headline in a certain newspaper states that "most stay at first job less than 2 years."
That headline is based on an online poll of 320 college graduates. Among those polled,
72% stayed at their first full-time job less than 2 years. a. Assuming that 50% is the true
percentage of graduates who stay at their first job less than two years, find the mean and
standard deviation of the numbers such graduates in randomly selected groups. Please if someone could help me with this, I have been working on a series of 50 pre-test questions and I am having trouble with this one, have been working on it for 2 hours!!

Question

A headline in a certain newspaper states that "most stay at first job less than 2 years."
That headline is based on an online poll of 320 college graduates. Among those polled,
72% stayed at their first full-time job less than 2 years. a. Assuming that 50% is the true 
percentage of graduates who stay at their first job less than two years, find the mean and 
standard deviation of the numbers such graduates in randomly selected groups. Please if someone could help me with this, I have been working on a series of 50 pre-test questions and I am having trouble with this one, have been working on it for 2 hours!!