could anyone help me out? i really don't understand z-scores... i have a final coming up and i can't contact my teachers because they are all on holidays.
for a given question, do i use the formula: z=(x-mean)/(standard deviation)? because when i am given the values for x, the mean, and standard deviation to find z, i always end up with a negative number or something that doesn't seem right. For example,
Mean = 45
Standard Deviation = 12
How do I find the z-score using these values? It can't be just plugging the values into the formula. How do I use the chart? As well, what if I am not given an x values? What do I do?