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You are given an unfair coin with probability of obtaining a head equal to 1/3, 000,000,000.
You toss this coin 6,000,000,000 times. Let A be the event that you get “tails for all the tosses”.
Let B be the event that you get “heads for all the tosses”.
i) Approximate P (A).
ii) Approximate P (A ∪ B)
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For (i), P(A) = = ,
where n = 3,000,000,000.
From Calculus, it is well known fact that
lim = as n --> oo.
So, P(A) = = = 0.1353 (approximately). ANSWER
For (ii), P(B) is extremely small and events A and B are mutially exclusive;
therefore, P(A U B) = P(A): P(B) contributes practically nothing.
Solved.