Intermediate November 2020 Unit 2 Q10
10.
(a) Caryl has two fair dice.
Dice A is a cube. It shows the numbers 1 to 6.
Dice B is a tetrahedron. It shows the numbers 1 to 4.
Caryl throws both dice.
What is the probability that she throws a 5 on dice A and a 3 on dice B? [2]
(b) Asif has a biased four-sided dice.
The dice shows the numbers 10, 20, 30 and 40.
The dice shows the numbers 10, 20, 30 and 40.
Asif throws the dice once.
The table below gives the probability of obtaining each number.
| Number | 10 | 20 | 30 | 40 |
|---|---|---|---|---|
| Probability | \(\dfrac{1}{2}\) | \(\dfrac{1}{5}\) | \(\dfrac{1}{5}\) | \(\dfrac{1}{10}\) |
What is the probability that Asif throws a 30 or a 40? [2]
| Scheme | Marks | Comments |
|---|---|---|
| \(\dfrac{1}{6}\) × \(\dfrac{1}{4}\) or equivalent | M1 | |
| = \(\dfrac{1}{24}\) ISW | A1 | Accept 0·0416… or 0·0417 or 0·042 for M1A1 M1A0 for ‘1 in 24’, ‘1:24’. |
| Scheme | Marks | Comments |
|---|---|---|
| \(\dfrac{1}{5}\) + \(\dfrac{1}{10}\) or equivalent. | M1 | |
| = \(\dfrac{3}{10}\) or equivalent. ISW | A1 |