Statistics and Probability, NAPX-E4-CA12, NAPX-E3-CA17

Question

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Worked Solution

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Variant 0

DifficultyLevel

609

Question

Billy has a sewing bag full of buttons where 65% of his buttons are red.

Billy takes a black button from his bag and sews it onto his shirt.

Billy then randomly takes a button from his sewing bag without looking.

What are the chances it is red?

Worked Solution

After taking a black button, the sewing bag has same number of red and less non-red coloured buttons.

∴\therefore Chances of a red are now greater than 65%

Question Type

Multiple Choice (One Answer)

Variables

Variable nameVariable value
question
Billy has a sewing bag full of buttons where 65% of his buttons are red. Billy takes a black button from his bag and sews it onto his shirt. Billy then randomly takes a button from his sewing bag without looking. What are the chances it is red?
workedSolution
After taking a black button, the sewing bag has same number of red and less non-red coloured buttons. $\therefore$ Chances of a red are now {{{correctAnswer}}}
correctAnswer
greater than 65%

Answers

Is Correct?Answer
✓

greater than 65%

x

equal to 65%

x

less than 65%

Variant 1

DifficultyLevel

607

Question

Novak has a basket full of tennis balls to practice with where 75% of the balls are Slazenger brand and 25% are Wilson brand.

Novak picks a Slazenger ball from the basket and practices his service.

If Novak immediately picks a second ball from the basket without looking, what are the chances it is a Slazenger ball?

Worked Solution

After serving with the first Slazenger ball, the basket now has same number of Wilson balls but one less Slazenger ball.

∴\therefore Chances of the second ball being a Slazenger is less than 75%

Question Type

Multiple Choice (One Answer)

Variables

Variable nameVariable value
question
Novak has a basket full of tennis balls to practice with where 75% of the balls are Slazenger brand and 25% are Wilson brand. Novak picks a Slazenger ball from the basket and practices his service. If Novak immediately picks a second ball from the basket without looking, what are the chances it is a Slazenger ball?
workedSolution
After serving with the first Slazenger ball, the basket now has same number of Wilson balls but one less Slazenger ball. $\therefore$ Chances of the second ball being a Slazenger is {{{correctAnswer}}}
correctAnswer
less than 75%

Answers

Is Correct?Answer
✓

less than 75%

x

equal to 75%

x

greater than 75%

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