In: Statistics and Probability
QUESTION 1 1. Use the data below to answer the following questions:
11.5
12.9
13.5
15.2
10.8
12.6
13.8
13.1
14.5
12.9
1. Calculate the sum of squares
2. Calculate the SEM.
3. Calculate a 95% confidence interval: Xbar +/- _________________. 1 points QUESTION 4 4. Calculate the 95% Lower Limit (Xbar - CI) 1 points
5. Calculate the 95% Upper Confidence Limit (Xbar + 95% CI)
6. You have a set of 15 observations of 10th rib pork backfat with a mean of 0.72 and s of 0.23. Construct a 95% IC for the true mean of 0.72 +/-___________________.
7. The upper 95% confidence limit is______________________.
8. The lower 95% confidence limit is ________________.
9. Calculate a 99% confidence interval with 0.72 +/- _____________________.
Values ( X ) | Σ ( Xi- X̅ )2 | |
11.5 | 2.4964 | |
12.9 | 0.0324 | |
13.5 | 0.1764 | |
15.2 | 4.4944 | |
10.8 | 5.1984 | |
12.6 | 0.2304 | |
13.8 | 0.5184 | |
13.1 | 0.0004 | |
14.5 | 2.0164 | |
12.9 | 0.0324 | |
Total | 130.8 | 15.196 |
Mean X̅ = Σ Xi / n
X̅ = 130.8 / 10 = 13.08
Sample Standard deviation SX = √ ( (Xi - X̅
)2 / n - 1 )
SX = √ ( 15.196 / 10 -1 ) = 1.2994
Sum of Squares = 15.196
SEM = S / √ n = 1.2994 / √ 10 = 0.4109
Confidence Interval
X̅ ± t(α/2, n-1) S/√(n)
t(α/2, n-1) = t(0.05 /2, 10- 1 ) = 2.262
13.08 ± t(0.05/2, 10 -1) * 1.2994/√(10)
Lower Limit = 13.08 - t(0.05/2, 10 -1) 1.2994/√(10)
Lower Limit = 12.1505
Upper Limit = 13.08 + t(0.05/2, 10 -1) 1.2994/√(10)
Upper Limit = 14.0095
95% Confidence interval is ( 12.1505 , 14.0095
)
Part 6)
Confidence Interval
X̅ ± t(α/2, n-1) S/√(n)
t(α/2, n-1) = t(0.05 /2, 15- 1 ) = 2.145
0.72 ± t(0.05/2, 15 -1) * 0.23/√(15)
Lower Limit = 0.72 - t(0.05/2, 15 -1) 0.23/√(15)
Lower Limit = 0.5926
Upper Limit = 0.72 + t(0.05/2, 15 -1) 0.23/√(15)
Upper Limit = 0.8474
95% Confidence interval is ( 0.5926 , 0.8474 )
Margin of Error = t(α/2, n-1) S/√(n) =
0.1274
0.72 +/- 0.1274
Lower Limit = 0.5926
Upper Limit = 0.8474
Part 9)
Confidence Interval
X̅ ± t(α/2, n-1) S/√(n)
t(α/2, n-1) = t(0.01 /2, 15- 1 ) = 2.977
0.72 ± t(0.01/2, 15 -1) * 0.23/√(15)
Lower Limit = 0.72 - t(0.01/2, 15 -1) 0.23/√(15)
Lower Limit = 0.5432
Upper Limit = 0.72 + t(0.01/2, 15 -1) 0.23/√(15)
Upper Limit = 0.8968
99% Confidence interval is ( 0.5432 , 0.8968
)
Margin of Error = t(α/2, n-1) S/√(n) = 0.1768
0.72 +/- 0.1768