SOLUTION: Find the t-value for a 90% confidence interval when the sample size is 20.

Click here to see ALL problems on Probability-and-statistics

Question 1047079: Find the t-value for a 90% confidence interval when the sample size is 20.
Found 2 solutions by stanbon, ewatrrr:
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
Find the t-value for a 90% confidence interval when the sample size is 20.
------------------
Ans:: t = -invT(0.10,19) = 1.3277
------------
Cheers,
Stan H.
-------------

Answer by ewatrrr(24785) (Show Source):
You can put this solution on YOUR website!

Hi
t-value for a 90% confidence interval when the sample size is 20
t-value where .95 of Distribution Curve is the left of that t-value
Can use Ti:
t = invT(.95, 19) Check with a table or statttek.com
CI 90% CI 95% CI 99%
DF t-value
0.1 0.05 0.01 0.001
1 6.31 12.71 63.66 636.62
2 2.92 4.3 9.93 31.6
3 2.35 3.18 5.84 12.92
4 2.13 2.78 4.6 8.61
5 2.02 2.57 4.03 6.87
6 1.94 2.45 3.71 5.96
7 1.89 2.37 3.5 5.41
8 1.86 2.31 3.36 5.04
9 1.83 2.26 3.25 4.78
10 1.81 2.23 3.17 4.59
11 1.8 2.2 3.11 4.44
12 1.78 2.18 3.06 4.32
13 1.77 2.16 3.01 4.22
14 1.76 2.14 2.98 4.14
15 1.75 2.13 2.95 4.07
16 1.75 2.12 2.92 4.02
17 1.74 2.11 2.9 3.97
18 1.73 2.1 2.88 3.92
19 2.09 2.86 3.88
20 1.72 2.09 2.85 3.85
Note: z-value
= CI z = value
90% z =1.645
92% z = 1.751
95% z = 1.96
98% z = 2.326
99% z = 2.576