Question

What iis the probability of scoring 100 in the quiz?

• A. $\frac{2}{9}$
• B. $\frac{2}{27}$
• C. $\frac{4}{27}$
• D. $\frac{1}{9}$

Answer 1

The correct option is B $\frac{2}{27}$

Solve on the basis of the following table. (C column represents "number of correct answers" and W column represents "number of wrong answers")
$\begin{array}{ccccccccc}& I-round& & & IIround& & & IIIround& \\ C& W& Netscore& C& W& Netscore& C& W& Netscore\\ 2& -& 50& 2& -& 50& 2& -& 80\\ 1& 1& 10& 1& 1& 10& 1& 1& 20\\ 0& -2& -20& 0& 2& -30& 0& 2& -40\end{array}$
There are $3\times 3\times 3=27$ possible scores. Out of these, there are only 2 ways of scoring 100.
Hence $\frac{2}{27}$ .