Nancy, who graduated from State University in June, Year 1, has just landed her first real job. She is excited because her salary is $4,000 per month. Nancy is single and has been planning all month about how she will spend her $4,000. When she received her first paycheck on June 30, Year 1, she was very disappointed. The amount of her check was only $3,100. Explain to Nancy why (generally) her check will not be for $4,000.