AQA GCSE · Question 06.2 · Statistical Measures and Calculations
What is the probability that a student, chosen at random, completed this piece of homework?
How to approach this question
1. Find the total number of students who completed the homework by adding the males and females in that column.
2. Find the total number of students in the class by adding all four numbers in the table.
3. The probability is the number of students who completed homework divided by the total number of students.
Full Answer
23/29
First, calculate the number of students who completed the homework:
Number of males who completed = 11
Number of females who completed = 12
Total who completed = 11 + 12 = 23.
Next, calculate the total number of students in the class:
Total students = (males who completed) + (males who did not) + (females who completed) + (females who did not)
Total students = 11 + 4 + 12 + 2 = 29.
The probability is the ratio of the number of students who completed the homework to the total number of students.
P(completed) = 23 / 29.
Common mistakes
✗ Only giving the number of students who completed (23) instead of the probability.
✗ Calculating the probability out of the wrong total, e.g., 23/11 or 23/12.
✗ Calculating the probability of not completing instead.
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