Explanation
Solution
Step 1: Find the probability of success (p) and failure (q)
Let the probability of failure be q and the probability of success be p.
According to the question, the experiment succeeds twice as often as it fails:
We know that p+q=1. Substituting p=2q:
Therefore, p=2×31=32.
Step 2: Identify parameters for Binomial Distribution
We need to find the probability of at least four successes (X≥4):
P(X≥4)=P(X=4)+P(X=5)+P(X=6)
Step 3: Calculate individual probabilities
Using the Binomial formula P(X=r)=(rn)prqn−r:
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For r=4:
P(X=4)=(46)(32)4(31)2=15×8116×91=729240
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For r=5:
P(X=5)=(56)(32)5(31)1=6×24332×31=729192
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For r=6:
P(X=6)=(66)(32)6(31)0=1×72964×1=72964
Step 4: Sum the probabilities
P(X≥4)=729240+729192+72964
Final Answer: The probability is 729496.