In a box there are only red pens, blue pens, black pens and green pens.
A pen is taken at random from the box.
The table shows the probabilities that the pen will be red or will be green.
| Colour | Red | Blue | Black | Green |
|---|---|---|---|---|
| Probability | 0.42 | 0.14 |
The probability that the pen will be black is three times the probability that the pen will be blue.
There are 28 green pens in the box.
Work out the number of black pens in the box.
Practise Eduqas GCSE Maths Probability with exam-style questions for Foundation and Higher tier. 212 questions, matched to the Eduqas GCSE Maths (C300QS) specification and written in Component 1 and Component 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
