A student committee on academic integrity has 42 ways to select a president and vice president from a group of candidates. The same person cannot be both president and vice president. How many candidates are there? Choose the correct choice from the following:  A) 7  B) 8  C) 9  D) 10  E) 11
xC1 * (x-1)C1=42   x^2 -x -42 =0   (X-7 (X+6) = 0   X= 7 , -6   -6 can't possible.   Hence 7 should be the answer   7
<result>A</result>
A student committee on academic integrity has 42 ways to select a president and vice president from a group of candidates. The same person cannot be both president and vice president. How many candidates are there?