Probability of Getting Exactly 6 Correct Answers
Given a multiple-choice test with 10 questions and 5 choices per question, we can calculate the probability of getting exactly 6 answers correct using the binomial probability formula:
Formula:
P(X = k) = ∫(n, k)pk(1-p)(n-k)
Parameters:
- n: Total questions = 10
- k: Correct answers = 6
- p: Probability of guessing correctly = 1/5 = 0.2
Calculations:
1. Calculate the binomial coefficient:
∆(10, 6) = ∫!10 / (6!(10-6)!) = 210
2. Apply the values in the formula:
P(X = 6) = 210 × (0.2)6 × (0.8)4
3. Calculate each component:
- (0.2)6 = 0.000064
- (0.8)4 = 0.4096
4. Final calculation:
P(X = 6) ≈ 210 × 0.000064 × 0.4096 ≈ 0.005529
Conclusion:
The probability that the student will get exactly 6 correct answers by guessing is approximately 0.005529, or 0.553%.
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