Well, if we can't find 0.42 on our chart, we can do the next best thing. The standard normal table without negative z-scores only deals with the right half of the normal curve and, therefore, with cumulative areas (to the left of the z-score) that are 0.5 or greater. The truth is, you don't really need one that has negative z-scores if you have a good intuitive grasp of the normal curve, particularly its symmetry. Some standard normal tables have an extra page for negative z-scores, and some don't. This ought to tell you that the z-score will be negative. One thing that you hopefully notice right away is that 0.42 is less than 0.5, and so the right boundary for this area will be to the left of the mean of 0. But it can be beneficial to try it this way, because this really forces you to get a visual representation of what is going on here. One difficulty with this is that there are multiple versions out there. I'll show one with minimal technology and one with reasonably available technology. As always, there are several options to solve this.
