Practice | Hashtable

1. In how many ways 2 students can be chosen from the class of 20 students?

A. 190

B. 180

C. 240

D. 390

Solution:

Number of ways

\begin{aligned} =^{20} C_{2} \\ = \frac{20!}{2! \times 18!} \\ = 20 \times \frac{19}{2} \\ = 190 \end{aligned}

You must login to add comments. Login now.