As both triangles are similar. <span>ΔRST ≅ ΔXYZ. it means RS = XY YZ = ST and XZ = RT Now given that RS = 13 which is equal to XY. Thus XY is equal to 13.</span>
Or, if you're familiar with the empirical rule and the basic properties of the normal distribution, you can use the fact that approximately of the distribution lies within two standard deviations of the mean, or
which means about of the distribution lies outside this interval, or