GCSE Maths Practice: conditional-probability

Question 10 of 10

This question illustrates conditional probability when one subgroup (Year 11) is excluded.

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\( \begin{array}{l}\text{In a school group, there are 12 Year 10, 8 Year 9, and 10 Year 11 students.} \\ \text{If a student is selected at random, what is the probability they are in Year 10,} \\ \text{given that they are not in Year 11?}\end{array} \)

Choose one option:

Remove the excluded subgroup first, then compute the fraction of the desired subgroup.

Focus only on the students not in Year 11 to calculate the probability for Year 10 students.