Question

Ross solved $20$ puzzles and the above scatterplot is plotted against the time consumed by the question and the number of clues it had. Calculate the probability, if a question is selected at random has less than six clues or takes fewer than $100$ seconds to solve or both.

• A. $10\%$
• B. $15\%$
• C. $85\%$
• D. $90\%$

Answer 1

The correct option is D $90\%$

In total there are $20$ question.

Out of these $3$ questions took more than $100$ secs and only $2$ of them had more than $6$ clues.

Thus the probability of selecting such a question which took more than $100$ sec and had more than $6$ clues is $\frac{2}{20}=0.1$. Therefore the required probability is $1-0.1=0.9=90\%$.