When taking a measurement from an instrument what place value should you write it to

I can only explain whis with an example :)

Basically, if you have an instrument that has the increments of a whole number, you wantb to have that whole number place a place value. For example, if you were to have a ruler with just whole inches, you would want to write it was 3.0. If it were to show increments between inches, it would be more like 3.2

the correct answer is:

a. formation of precipitation