Four cards each show a different 2-digit number. The average of the four numbers is 85. What is the smallest possible number on the cards?
Need a hint?
Make three of the numbers as large as you can, then find what the fourth number must be.
Worked answer
- Total of the four numbers = 85 × 4 = 340.
- To make the smallest number as small as possible, the other three must be as large as possible: 99, 98 and 97, which sum to 294.
- Smallest number = 340 − 294 = 46.
Answer: 46
The mistake this question tests
Habit
Average and total
Pupils often forget the four numbers must be different and use 99, 99 and 99, getting 340 − 297 = 43.
How to fix it at home →More PSLE whole numbers questions
MCQ · 1m
The total mass of 5 boxes is 2015 g
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See the answer →Short answer · 2mThe average mass of a basket of apples is 150 g
See the answer →Practise PSLE whole numbers until the mistakes stop.
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