# Math Help - z-scoressss

1. ## z-scoressss

In a normal distribution with mean 3 and variance 49, what are the upper and lower limit scores for the middle 50% of the data?

-how do I find the answer from the z-score table?

2. Originally Posted by perron
In a normal distribution with mean 3 and variance 49, what are the upper and lower limit scores for the middle 50% of the data?

-how do I find the answer from the z-score table?
Let $\Pr(X > x_2) = 0.25$ and $\Pr(X < x_1) = 0.25$. Your task is to find the value of $x_2$ and $x_1$.

$\Pr(Z > z*) = 0.25 \Rightarrow \Pr(Z < z*) = 0.75 \Rightarrow z* = 0.6745$ (using whatever way you've been taught to deal with an inverse normal situation).

Therefore $z* = \frac{x_2 - 3}{7}$. Solve for $x_2$. Use the symmetry of the normal distribution to therefore get $x_1$.