Quiz-Tree

Hard - Quiz 1

How deep does your probability reasoning go? Work through Bayes-style conditionals, geometric probability, dependent draws, and reverse inference from rates.

Question 1 of 5
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Question 1
A survey of 300 shoppers asked about their preferred product type. The results are organized by income level in the table below. \[\begin{array}{|c|c|c|c|} \hline & \textbf{Store Brand} & \textbf{Name Brand} & \textbf{Total} \\ \hline \textbf{Under \$50k} & 90 & 60 & 150 \\ \textbf{\$50k and over} & 40 & 110 & 150 \\ \hline \textbf{Total} & 130 & 170 & 300 \\ \hline \end{array}\] Given that a randomly selected shopper prefers name brand, what is the probability that the shopper earns $50,000 or more?
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A circular dartboard has a radius of 10 inches. The bullseye at the center is a circle with a radius of 2 inches. If a dart lands at a random point on the board, what is the probability it lands in the bullseye?
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A factory uses two machines. Machine A produces 60% of all items and has a 5% defect rate. Machine B produces the remaining 40% and has a 3% defect rate. If a randomly selected item is found to be defective, what is the probability it was produced by Machine A?
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A college program received 120 applications. The results are shown below. \[\begin{array}{|c|c|c|c|c|} \hline & \textbf{Accepted} & \textbf{Waitlisted} & \textbf{Rejected} & \textbf{Total} \\ \hline \textbf{In-state} & 30 & 15 & 15 & 60 \\ \textbf{Out-of-state} & 10 & 20 & 30 & 60 \\ \hline \textbf{Total} & 40 & 35 & 45 & 120 \\ \hline \end{array}\] Two applicants are selected at random without replacement. Given that the first applicant selected is an accepted in-state student, what is the probability the second applicant selected is also an accepted in-state student?
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In a group of 200 adults, 100 exercise regularly. Of those who exercise regularly, 80% report good sleep quality. Of those who do not exercise regularly, 50% report good sleep quality. If an adult from the group is selected at random and reports good sleep quality, what is the probability that this person exercises regularly?
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