18 venture-capital investments in the fiber optics business sector
Mean = 6.33 , standard deviation = 2.04 (also Pop sd)
90% confidence interval
ME = 1.74 (2.04/sqrt(18))
CI: 6.33-ME < u < 6.33 + ME
.....
50% confidence interval ...
ME = .689 (2.04/sqrt(18))
CI: 6.33-ME < u < 6.33 + ME
.......
minimum sample size required to have a margin of error of $0.05 million with a 90% confidence interval.
.05 = 1.645((2.04/sqrt(n))
n =
.......
DF Probability, p 2-tailed
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 2.11 2.9 3.97
18 1.73 2.1 2.88 3.92