Question

When working with a sample of size 28, find the area under a t-curve:

(a) Above -1.2.
ANSWER:   

(b) Below 0.6.
ANSWER:   

(c) Between -1.8 and 1.6.
ANSWER:   

Answer 1

Using Excel functions, we can find the area under t-curve

degrees of freedom =n-1 = 28-1 = 27

a) Above -1.2

T.DIST.RT(x, df) = T.DIST.RT(-1.2, 27) = 0.8797

**RT stands for right tailed, since the curve is above one value we used RT function

b) Below 0.6

T.DIST(x, df, cumulative) = T.DIST(0.6, 27, TRUE) = 0.7232

**here left tailed is used and cumulative argument is for cdf

c) Between -1.8 and 1.6

T.DIST(1.6, 27, TRUE) - T.DIST(-1.8, 27, TRUE) = 0.9394 - 0.0415 = 0.8979