Returns the result of a Student's t-test.
TTEST(data1, data2, mode, type)
data1 and data2 are ranges or arrays (possibly of different size) containing numbers, on which the t-test is performed.
1 for a one-tailed t-test
2 for a two-tailed t-test.
1 for paired samples
2 for two samples with equal variance
3 for two samples with unequal variance.
TTEST(A2:A20, B2:20, 2, 3)
returns the result of a two-tailed Student's t-test for two samples with unequal variance, using the data in A2:A20 and B2:20.