A medium question on averages for P5, with a step-by-step solution, diagrams and the answer. Averages appear in the Hua Xia Cup's P4 and P5 first rounds, qualifying rounds and finals.
The question
A class sits a maths test in two groups.
Group A has 10 pupils with an average of 66; group B has 8 pupils with an average of 93.
What is the average for the whole class?
Show the hints (2)
💡Hint 1: The groups are different sizes, so you can't just average the two averages. Find each group's total first.
💡Hint 2: The class total divided by the number in the class gives the class average.
Worked solution
Have a go first, then read the solution step by step.
1.Group A total: 66 × 10 = 660; group B total: 93 × 8 = 744.
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