Foundation June 2018 Paper 1R Q10
10 There are 20 counters in bag X.
7 of the counters are green.
10 of the counters are red.
The rest of the counters are blue.
Ruth takes at random a counter from bag X.
(a) Write down the probability that the counter is red. (1)
(b) Work out the probability that the counter is blue. (1)
Ruth puts the counter back into bag X.
Bag Y only contains green counters, red counters and blue counters.
In bag Y there are,
2 more green counters than in bag X
1 more red counter than in bag X
2 more blue counters than in bag X
Adam takes at random a counter from bag Y.
Ruth takes at random a counter from bag X.
(c) Who has the greater probability of taking a green counter, Adam or Ruth?
Show your working clearly. (3)
Show your working clearly. (3)
| Scheme | Marks |
|---|---|
| \(\dfrac{10}{20}\) | B1 |
| (1) |
Notes
B1: Accept 0.5, \(\dfrac{1}{2}\), \(\dfrac{5}{10}\), 50%
| Scheme | Marks |
|---|---|
| \(\dfrac{3}{20}\) | B1 |
| (1) |
Notes
B1: Accept 0.15, 15%
| Scheme | Marks |
|---|---|
| \(\dfrac{9}{20 + 1 + 2 + 2}\) or \(\dfrac{7}{20}\) | M1 |
| \(\dfrac{9}{25} = 0.36\) and \(\dfrac{7}{20} = 0.35\) | M1 |
| Adam with reason | A1 |
| (3) | |
| (5 marks) |
Notes
M1: for at least one probability
M1: for both correct probabilities
A1: Adam with 0.36 and 0.35 clearly seen oe