The expectation of a random variable is given by the integral of $x$ times its probability density function. In this case, the expectation $E(X)$ is given by:
$$E(X) = \int_{1}^{8} x \cdot f(x) \, dx = \int_{1}^{8} x \cdot \frac{8}{7x^{2}} \, dx = \int_{1}^{8}
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