Question 13
There are three boxes labelled 1, 2 and 3. Each box contains different numbers of different coloured marbles.
- The number of yellow marbles is half the sum of the red and blue marbles.
- There are more blue marbles than red marbles.
- Box 1 has 10 marbles.
- The total number of marbles is 60.
How many blue marbles are there?
**Assumption for this self-study exercise:** Each box contains marbles of just one colour, and the three boxes contain red, yellow and blue marbles, one colour per box. This is the interpretation used by the source solution; the original wording does not state it clearly.
Enter one whole number, without units.
- The number of yellow marbles is half the sum of the red and blue marbles.
- There are more blue marbles than red marbles.
- Box 1 has 10 marbles.
- The total number of marbles is 60.
How many blue marbles are there?
**Assumption for this self-study exercise:** Each box contains marbles of just one colour, and the three boxes contain red, yellow and blue marbles, one colour per box. This is the interpretation used by the source solution; the original wording does not state it clearly.
Enter one whole number, without units.