1. **Problem Statement:** We are given that Jamie has a probability of $\frac{1}{3}$ to hit a target on any attempt.
2. The probability that he hits the target for the first time on his $n^{th}$ attempt is given as $\frac{64}{2187}$.
3. We want to find the value of $n$.
4. **Formula Used:** The probability that the first success occurs on the $n^{th}$ trial in a sequence of independent trials with success probability $p$ is given by the geometric distribution:
$$P(X=n) = (1-p)^{n-1} p$$
where $p = \frac{1}{3}$ is the probability of hitting the target.
5. Substitute $p = \frac{1}{3}$ and $P(X=n) = \frac{64}{2187}$:
$$\left(1 - \frac{1}{3}\right)^{n-1} \times \frac{1}{3} = \frac{64}{2187}$$
6. Simplify $1 - \frac{1}{3} = \frac{2}{3}$:
$$\left(\frac{2}{3}\right)^{n-1} \times \frac{1}{3} = \frac{64}{2187}$$
7. Multiply both sides by 3:
$$\left(\frac{2}{3}\right)^{n-1} = \frac{64}{2187} \times 3 = \frac{192}{2187}$$
8. Note that $64 = 2^6$ and $2187 = 3^7$, so:
$$\frac{192}{2187} = \frac{64 \times 3}{3^7} = \frac{2^6 \times 3}{3^7} = 2^6 \times 3^{1-7} = 2^6 \times 3^{-6}$$
9. Also, rewrite the left side:
$$\left(\frac{2}{3}\right)^{n-1} = 2^{n-1} \times 3^{-(n-1)}$$
10. Equate the powers of 2 and 3:
$$2^{n-1} \times 3^{-(n-1)} = 2^6 \times 3^{-6}$$
11. This implies:
$$n - 1 = 6$$
and
$$-(n - 1) = -6$$
12. Solve for $n$:
$$n = 7$$
**Final answer:** $n = 7$
Geometric Probability F10A6D
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