Intermediate November 2018 Unit 1 Q6
6. In this question, you will be assessed on the quality of your organisation, communication and accuracy in writing.
A box contains five identical balls numbered 1 to 5 respectively.
One ball is chosen at random from the box.
Its number is recorded and the ball is replaced in the box.
This process was carried out 75 times in total.
How many times would you expect an even-numbered ball to have been chosen?
You must show all your working. [3 + 2 OCW]
| Scheme | Marks | Comments |
|---|---|---|
| Recognising that each number has a one in five chance of being chosen. | B1 | May be expressed in words e.g. ‘ 2 (even) numbers out of 5’, ‘ each number has a one in 5 chance’ OR as a probability e.g . sight of 2/5, ‘(probability of choosing each ball =) 1/5’ B0 if no reference to ‘ out of 5’ or ‘in 5’. |
| (Expected number of even numbers =) \(\dfrac{2}{5} \times 75\) | M1 | M1 for 1/5 × 75 × 2 or equivalent. M1 implies the B1. |
| = 30 | A1 | 30/75 gains B1M1A0 if 30 on its own is not shown. |
| Organisation and Communication. | OC1 | For OC1, candidates will be expected to:
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| Accuracy of writing. | W1 | For W1, candidates will be expected to:
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