\(\begin{array}{c|c} \text{Age in years} & 10 & 11 & 12 \\ \hline \text{Number of pupils} & 6 & 27 & 7\end{array}\)
The table above shows the number of pupils in each age group in a class. What is the probability that a pupil chosen at random is at least 11 years old?
- \(\frac{27}{40}\)
-
\(\frac{17}{20}\)
- \(\frac{33}{40}\)
- \(\frac{3}{20}\)
The correct answer is: B
Explanation
Total number of pupils = 7 + 27 + 6 = 40
n(at least 11 years old) = 27 + 7 = 34.
P(picking a pupil who is at least 11 years old) = \(\frac{34}{40} = \frac{17}{20}\).