CUET · MATHS · PYQ PAPER 2023
The probability of guessing correctly atleast 8 out of 10 answers on a true false type examination is :
- A \(\frac{7}{64}\)
- B \(\frac{7}{128}\)
- C \(\frac{45}{1024}\)
- D \(\frac{7}{41}\)
Answer & Solution
Correct Answer
(B) \(\frac{7}{128}\)
Step-by-step Solution
Detailed explanation
\( P(X \ge 8) = P(X=8) + P(X=9) + P(X=10) \) \( P(X=k) = C(10, k) (\frac{1}{2})^{10} \) \( P(X \ge 8) = C(10,8)(\frac{1}{2})^{10} + C(10,9)(\frac{1}{2})^{10} + C(10,10)(\frac{1}{2})^{10} \) \( P(X \ge 8) = (45 + 10 + 1) (\frac{1}{2})^{10} \)…
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