Answer:
The 99 % confidence interval on the basis of mean is ( 21.7393 ; 22.0257)
Explanation:
Mean = Sum of observations / Number of observations
Mean = 21.88 +21.76 +22.14 +21.63+ 21.81 +22.12+ 21.97+ 21.57+ 21.75+ 21.96 +22.20 +21.80/ 12
Mean =x`= 262.59/12= 21.8825
Standard Deviation = s= ∑x²/n - ( ∑x/n)²
∑x²/n= 478.7344 +473.4976 + 490.1796+467.8569+ 475.6761 + 489.2944+ 482.6809+ 465.2649+ 473.0625+ 482.2416 +492.84 + 475.24/ 12
∑x²/n= 5746.5689/12= 478.8807 = 478.881
Standard Deviation = s= ∑x²/n - ( ∑x/n)²
s= 478.881- (21.8825)²= 478.881-478.843= 0.037
The confidence limit 99% for the mean will be determined by
x` ± α(100-1) √s/n
Putting the values in the above equation
= 21.8825 ± 2.58 √0.037/12
Solving the square root
= 21.8825 ± 2.58 (0.05549)
Multiplying the square root with 2.58
=21.8825 ± 0.1432
Adding and subtracting would give
21.7393 ; 22.0257,
Hence the 99 % confidence interval on the basis of mean is ( 21.7393 ; 22.0257)