JEE Mains · Maths · STD 12 - 13. probability
A fair coin is tossed a fixed number of times. If the probability of getting \(7\) heads is equal to probability of getting \(9\) heads, then the probability of getting \(2\) heads is
- A \(\frac{15}{2^{13}}\)
- B \(\frac{15}{2^{12}}\)
- C \(\frac{15}{2^{8}}\)
- D \(\frac{15}{2^{14}}\)
Answer & Solution
Correct Answer
(A) \(\frac{15}{2^{13}}\)
Step-by-step Solution
Detailed explanation
Let the coin be tossed \(n\) -times \(P ( H )= P ( T )=\frac{1}{2}\) \(P (7\) heads \()={ }^{n} C _{7}\left(\frac{1}{2}\right)^{ n -7}\left(\frac{1}{2}\right)^{7}=\frac{{ }^{n} C _{7}}{2^{ n }}\) \(P (9\) heads…
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