4400 Higher June 2007 Paper 4 Q8
8 A bag contains some marbles.
The colour of each marble is red or blue or green or yellow.
A marble is taken at random from the bag.
The table shows the probability that the marble is red or blue or green.
| Colour | Probability |
|---|---|
| Red | 0.1 |
| Blue | 0.2 |
| Green | 0.1 |
| Yellow |
(a) Work out the probability that the marble is yellow. (2)
(b) Work out the probability that the marble is blue or green. (2)
The probability that the marble is made of glass is 0.8
(c) Beryl says “The probability that the marble is green or made of glass is 0.1 + 0.8 = 0.9”
Is Beryl correct?
Give a reason for your answer. (2)
Is Beryl correct?
Give a reason for your answer. (2)
| Scheme | Marks |
|---|---|
| 1 − (0.1 + 0.2 + 0.1) or 1 − 0.4 oe | M1 |
| 0.6 | A1 |
| (2) |
Notes
M1: or 0.6 in table
A1: allow in table if not contrad on line
| Scheme | Marks |
|---|---|
| 0.2 + 0.1 or 1 − (‘0.6’ + 0.1) | M1 |
| 0.3 | A1 |
| (2) |
Notes
M1: or 0.3 seen
| Scheme | Marks |
|---|---|
| (Poss) overlap or mut excl or doesn’t wk for B or Y No or poss or poss yes | B2 |
| (2) | |
| (6 marks) |
Notes
B2: Can’t tell & (No or poss) B1
Correct reason only: B1
Incorrect reason: B0
Unqualified Yes: B0