A normal distribution has a mean of 98 and a standard deviation of 4 . Find the $z$-score for a data value of 90.
Round to two decimal places

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So, the z-score for a data value of 90 is $\boxed{-2.00}$.

Steps

Step 1 ：Given that the mean ($\mu$) is 98, the standard deviation ($\sigma$) is 4, and the data value ($X$) is 90.

Step 2 ：The formula to calculate the z-score is $Z = \frac{X - \mu}{\sigma}$.

Step 3 ：Substitute the given values into the formula: $Z = \frac{90 - 98}{4} = -2.0$.

Step 4 ：So, the z-score for a data value of 90 is $\boxed{-2.00}$.