# Confidence intervals for one population mean when S.D. is unknown /t-curve

For a t-curve with df = 8, find each t-value and illustrate your results graphically.

a.The t-value having area 0.05 to its right.

b. t 0.10

c.The t-value having area 0.01 to its left

(hint: A t-curve is symmetric about 0.)

d.The two t-values that divide the area under the curve into a middle 0.95 area and two outside 0.025 areas

https://brainmass.com/statistics/confidence-interval/confidence-intervals-one-population-mean-4698

#### Solution Preview

please refer to the attachment for graphs

a.

X

0.05

t*=1.860

Pr(X<=t*)=1-0.05=0.95, and is a one-tailed distribution, with df=8

From the t-table, t*(8, 0.95) = 1.860

b. It's not clear in your posting what is t0.10, I will take it as the t-value having area 0.10 to its ...

#### Solution Summary

For a t-curve with df = 8, find each t-value and illustrate your results graphically.

a.The t-value having area 0.05 to its right.

b. t 0.10

c.The t-value having area 0.01 to its left

(hint: A t-curve is symmetric about 0.)

d.The two t-values that divide the area under the curve into a middle 0.95 area and two outside 0.025 areas