For a given set of data, the standard score, $z$, corresponding to the raw score, $x$, is given by $z=\dfrac{x-\mu}{\sigma}$, where $\mu$ is the mean of the set and $\sigma$ is the standard deviation. If, for a set of scores, $\mu=78$ and $\sigma = 6$, which of the following is the raw score, $x$, corresponding to $z=2$ ?

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We can simply substitute values into the equation.

$$z=\frac{x-\mu}{\sigma}$$ $$2=\frac{x-78}{6}$$ $$12 = x-78$$ $$x = \boxed{90}$$