In how many ways 2 students can be chosen from the class of 20 students?  Pick one:
A) 190  B) 180  C) 240  D) 390  E) None
Solution: Number of ways = 20C2 = 20!/(2! 18!)   = 20*19/2= 
<gadget id="calculator">20*19/2</gadget>
<output>190</output>
190.   190nswer: Option 190
<result>A</result>
In how many ways 2 students can be chosen from the class of 20 students?