4MA0 Foundation January 2016 Paper 2 Q21
21 A box contains toy cars.
Each car is red or blue or black or silver.
Emily takes at random a car from the box.
The table shows the probabilities that Emily takes a red car or a blue car or a black car.
| Colour of car | Probability |
|---|---|
| red | 0.20 |
| blue | 0.05 |
| black | 0.15 |
| silver |
(a) Work out the probability that Emily takes a silver car. (2)
Emily puts the car back into the box.
There are 6 blue cars in the box.
(b) Work out the total number of cars in the box. (2)
| Scheme | Marks |
|---|---|
| 1 – (0.2 + 0.05 + 0.15) or 1 – 0.4 | M1 |
| 0.6 | A1 |
| (2) |
Notes
A1: oe
| Scheme | Marks |
|---|---|
6 + 6 × 4 + 6 × 3 + 6 × 12 (=6 + 24 + 18 + 72) or 6 × 20 or \(\dfrac{6}{0.05}\) | M1ft |
| 120 | A1 |
| (2) |
Notes
M1ft: \(6 + 6 \times 4 + 6 \times 3 + \dfrac{\text{‘0.6’}}{0.05} \times 6\)
(allow M1 for 3 correct products out of 4)