Comparing samples with a t-test

How can you be sure a sample is the same or different compared to a population or other sample? As you just learned sample independence can be tested with a T.TEST()!

T.TEST(range1, range2, tails, type)

In this exercise you are examining data from a farm. Prior to introducing a new fertilizer, 10 plant heights were measured. After the new fertilizer was used another 10 plants were measured. You will perform a t-test to understand if the plant heights in the samples are in fact different. This is a two-tailed test because the heights are either above or below the original sample, "tails" to either side of the original distribution. The type is 2 because the samples are not from the same subjects but they have the same variance. Had they been the same plants before and after fertilizer treatment, it would be a "paired" t-test which is type 1.