S1 - variance and standard deviation help!

I can't figure out how to answer a question like this or how you go about it. Any help appreciated.

In a certain district, the mean annual rainfall is 80cm with standard deviation 4cm.
1) One year it was 90cm. Was this an exceptional year?
2) The next year had a total of 78cm. Was that exceptional?

Draw a picture. Always helps. Even if it's just to sort information or make it understandable all at once.

I know this sounds stupid but I really have no idea where to start, I am not sure what I could draw.

I can't figure out how to answer a question like this or how you go about it. Any help appreciated.

In a certain district, the mean annual rainfall is 80cm with standard deviation 4cm.
1) One year it was 90cm. Was this an exceptional year?
2) The next year had a total of 78cm. Was that exceptional?

Draw the distribution. Then mark in the mean and map out one or two standard deviations. So here it's 80 for the mean and 84 and 88 for 1 and 2 sd. So 90 is more than 2 sd's away from the mean - that's pretty far, no? Whereas 78 is only half a sd away, that's close.

For a roughly symmetrical distribution, 95% of the data lies within 4 standard deviations of the mean (in your case 95% of the data will lie between 72-88 as the mean is 80 and SD=4).