A baker stored flour in two sacks, Sack P and Sack Q. Sack P contained three times as much flour as Sack Q. In Sack P, 13 of the flour was wholemeal flour. In Sack Q, 34 of the flour was wholemeal flour. What fraction of all the flour was wholemeal flour?
Need a hint?
Try letting the amount in Sack Q be 1 unit. How many units are in Sack P? Then find the wholemeal flour in each sack separately before adding them together.
Worked answer
- Let the amount of flour in Sack Q be 1 unit.
- Then Sack P has 3 units of flour.
- Total flour = 3 + 1 = 4 units.
- Wholemeal flour in Sack P = 13 of 3 units = 1 unit.
- Wholemeal flour in Sack Q = 34 of 1 unit = 34 unit.
- Total wholemeal flour = 1 + 34 = 134 units.
- Fraction of all flour that is wholemeal = 134 ÷ 4 = 74 ÷ 4 = 716.
Answer: 7/16
The mistake this question tests
Habit
Fraction of a remainder
A common mistake is to add 13 and 34 directly to get 1312, or to average them. This is wrong because the two fractions refer to different total amounts of flour in each sack.
How to fix it at home →Wrong answers children often give:
- 13/12 Calculation slip
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