Foundation June 2025 Paper 2 Q15
15 There are 20 buttons in a box.
There are
6 blue buttons
9 green buttons
5 red buttons.
Jai puts 12 more buttons in the box.
These buttons are either blue buttons or red buttons.
Jai is going to pick at random one button from the box.
The probability that this button will be blue is \(\dfrac{1}{4}\)
How many more red buttons did Jai put in the box?
You must show all your working. (4)
| Answer | Mark | Mark scheme |
|---|---|---|
| 10 | P1 | for process to find total number of buttons \(20 + 12\ (= 32)\) |
| P1 | for process to work with probability, eg \(\text{``}32\text{''} \div 4\ (= 8)\) or \(\text{``}32\text{''} \div 4 \times 3\ (= 24)\) | |
| P1 | for process to find number of extra blue buttons required, eg \(\text{``}8\text{''} - 6\ (= 2)\) or for process to find number of extra reds, eg \(12 - (\text{``}8\text{''} - 6)\) or for process to find new total number of red buttons, eg \((6 + 5 + 12) - \text{``}8\text{''}\ (= 15)\) or \(\text{``}32\text{''} - \text{``}8\text{''} - 9\ (= 15)\) or \(\text{``}24\text{''} - 9\ (= 15)\) | |
| A1 | (dep P2) cao |
Additional guidance
May be implied by \(\dfrac{\text{``}8\text{''}}{\text{``}32\text{''}}\)
May be implied by 8 : 9 : 15
or \(\dfrac{\text{``}10\text{''}}{\text{``}32\text{''}}\)
Answer of 10 only scores no marks