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- #1

- Apr 14, 2013

- 4,004

2 coins are thrown 20 times. I want to calculate the probability

(a) to achieve exactly 5 times the Tail/Tail

(b) to achieve at least 2 times Tail/Tail

If we throw the 2 coins once the probability that we get Tail/Tail is equal to $\frac{1}{2}\cdot \frac{1}{2}=\frac{1}{4}$, or not?

Is the probability then at (a) equal to $\left (\frac{1}{4}\right )^{20}$ ?

Could you give me a hint for (b) ?