A three-person committee must be chosen from a group of 7 professors and 15 graduate students. If at least one of the people on the committee must be a professor, how many different groups of people could be chosen for the committee?  Choose the most appropriate option
A) A)70 B) B)1085 C) C)630 D) D)1,260 E) E)1,980
Total number of ways to select at least one professor = Number of ways to select 3 people from 15 students and 7 professors - Number of ways to select 3 people from 15 student (i.e. without including any professor)   = 22C3 - 15C3 = 1540 - 455= 
<gadget id="calculator">1540 - 455</gadget>
<output>1_085</output>
1085   ANSWER:1085
<result>B</result>
A three-person committee must be chosen from a group of 7 professors and 15 graduate students. If at least one of the people on the committee must be a professor, how many different groups of people could be chosen for the committee?