Probability, NAPX-K2-12
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Variant 0
DifficultyLevel
438
Question
Eight buttons, numbered 1 to 8, are placed in a bag.
Robin picks three buttons out of the bag without looking.
Once chosen, a button is not put back into the bag.
The first button is number 2.
Which of the following cannot happen?
Worked Solution
Once number 2 is picked, it cannot be
picked again (no replacement).
∴ The third button cannot be 2.
Question Type
Multiple Choice (One Answer)
Variables
| Variable name | Variable value |
| question | Eight buttons, numbered 1 to 8, are placed in a bag.
Robin picks three buttons out of the bag without looking.
Once chosen, a button is not put back into the bag.
The first button is number 2.
Which of the following cannot happen? |
| workedSolution | Once number 2 is picked, it cannot be
picked again (no replacement).
$\therefore$ The third button cannot be 2. |
| correctAnswer | |
Answers
| Is Correct? | Answer |
| x | The second button is even. |
| ✓ | |
| x | The second button is odd. |
| x | |
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Variant 1
DifficultyLevel
441
Question
Six buttons, numbered 1 to 6, are placed in a bag.
Barney picks four buttons out of the bag without looking.
Once chosen, a button is not put back into the bag.
The first three buttons Barney chose, in order, are 5, 1 and 3.
Which of the following cannot happen?
Worked Solution
Once numbers 5, 3 and 1 are picked, they cannot be
picked again (no replacement).
∴ The 4th button chosen cannot be odd → only even numbers left.
Question Type
Multiple Choice (One Answer)
Variables
| Variable name | Variable value |
| question | Six buttons, numbered 1 to 6, are placed in a bag.
Barney picks four buttons out of the bag without looking.
Once chosen, a button is not put back into the bag.
The first three buttons Barney chose, in order, are 5, 1 and 3.
Which of the following cannot happen? |
| workedSolution | Once numbers 5, 3 and 1 are picked, they cannot be
picked again (no replacement).
$\therefore$ The 4th button chosen cannot be odd $\rightarrow$ only even numbers left. |
| correctAnswer | The 4th button chosen is odd. |
Answers
| Is Correct? | Answer |
| x | The 4th button chosen is even. |
| x | The 4th button chosen is 6. |
| x | The 4th button chosen is 2. |
| ✓ | The 4th button chosen is odd. |
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Variant 2
DifficultyLevel
439
Question
Seven buttons, numbered 1 to 7, are placed in a bag.
Zac picks four buttons out of the bag without looking.
Once chosen, a button is not put back into the bag.
The first two buttons Zac chose are 6 and 2.
Which of the following cannot happen?
Worked Solution
Once numbers 6 and 2 are picked, they cannot be
picked again (no replacement).
∴ The 3rd and 4th picks cannot both be even → only one even number is left.
Question Type
Multiple Choice (One Answer)
Variables
| Variable name | Variable value |
| question | Seven buttons, numbered 1 to 7, are placed in a bag.
Zac picks four buttons out of the bag without looking.
Once chosen, a button is not put back into the bag.
The first two buttons Zac chose are 6 and 2.
Which of the following cannot happen? |
| workedSolution | Once numbers 6 and 2 are picked, they cannot be
picked again (no replacement).
$\therefore$ The 3rd and 4th picks cannot both be even $\rightarrow$ only one even number is left. |
| correctAnswer | The 3rd and 4th pick can both be even. |
Answers
| Is Correct? | Answer |
| x | |
| ✓ | The 3rd and 4th pick can both be even. |
| x | |
| x | |