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In a multiple choice question, there are...

In a multiple choice question, there are four alternative answers of which one or more than one is correct A candidate will get marks on the question only if he ticks the correct answer. The candidate decides to tick answers at a random. If he is allowed up to three chances to answer the question, then find the probability that he will get marks on it.

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To solve the problem step by step, let's break it down: ### Step 1: Understanding the Problem We have a multiple-choice question with 4 options, and one or more of these options can be correct. The candidate can randomly tick answers and has up to 3 chances to get it right. We need to find the probability that he will get marks for the question. ### Step 2: Total Combinations of Answers The total number of ways to choose one or more options from 4 options can be calculated using the formula for combinations. The possible combinations are: - Choosing 1 option from 4: \( C(4, 1) = 4 \) - Choosing 2 options from 4: \( C(4, 2) = 6 \) - Choosing 3 options from 4: \( C(4, 3) = 4 \) - Choosing all 4 options: \( C(4, 4) = 1 \) So, the total number of ways to choose one or more options is: \[ 4 + 6 + 4 + 1 = 15 \] ### Step 3: Probability of Correct Answer Out of these 15 combinations, only 1 combination is the correct one. Therefore, the probability of getting the correct answer in one trial is: \[ P(\text{Correct}) = \frac{1}{15} \] And the probability of not getting the correct answer is: \[ P(\text{Incorrect}) = 1 - P(\text{Correct}) = 1 - \frac{1}{15} = \frac{14}{15} \] ### Step 4: Probability of Getting Marks in 3 Trials The candidate has 3 chances to get the correct answer. We can find the probability of getting at least one correct answer in these 3 trials. This can be calculated using the complement rule: \[ P(\text{At least 1 correct in 3 trials}) = 1 - P(\text{All incorrect in 3 trials}) \] The probability of getting all answers incorrect in 3 trials is: \[ P(\text{All incorrect}) = P(\text{Incorrect})^3 = \left(\frac{14}{15}\right)^3 \] Calculating \( \left(\frac{14}{15}\right)^3 \): \[ \left(\frac{14}{15}\right)^3 = \frac{14^3}{15^3} = \frac{2744}{3375} \] Now, substituting this back into our equation: \[ P(\text{At least 1 correct}) = 1 - \frac{2744}{3375} = \frac{3375 - 2744}{3375} = \frac{631}{3375} \] ### Step 5: Final Probability Calculation Thus, the probability that the candidate will get marks on the question after 3 trials is: \[ P(\text{Marks}) = \frac{631}{3375} \] ### Conclusion The final answer is: \[ \text{Probability that the candidate will get marks} = \frac{631}{3375} \]

To solve the problem step by step, let's break it down: ### Step 1: Understanding the Problem We have a multiple-choice question with 4 options, and one or more of these options can be correct. The candidate can randomly tick answers and has up to 3 chances to get it right. We need to find the probability that he will get marks for the question. ### Step 2: Total Combinations of Answers The total number of ways to choose one or more options from 4 options can be calculated using the formula for combinations. The possible combinations are: - Choosing 1 option from 4: \( C(4, 1) = 4 \) ...
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