Age in years
10
11
12
Number of pupils
6
27
7
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?
A
\(\frac{27}{40}\)
B
\(\frac{17}{20}\)
C
\(\frac{33}{40}\)
D
\(\frac{3}{20}\)
Verified Correct Answer: B.
Step-by-Step Mathematical Solution
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) = \(\frac{34}{40} = \frac{17}{20}\).
Source: Myschool Past Questions Archive (Record #31020)