Age in years101112Number of pupils6277 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...

$\begin{array}{cccc}\text{Age in years}& 10& 11& 12\\ \text{Number of pupils}& 6& 27& 7\end{array}$

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?

Answer Details

To find the probability that a pupil chosen at random is at least 11 years old, we need to add up the number of pupils in the 11-year-old and 12-year-old age groups, since they are the ones who are at least 11 years old. From the table, we can see that there are 27 pupils who are 11 years old and 7 pupils who are 12 years old. Therefore, the total number of pupils who are at least 11 years old is 27 + 7 = 34. To find the probability, we divide the number of pupils who are at least 11 years old by the total number of pupils in the class. From the table, we can see that the total number of pupils in the class is 6 + 27 + 7 = 40. Therefore, the probability that a pupil chosen at random is at least 11 years old is: 34/40 = 17/20 So the answer is: 17/20.