Answer:
The 99 % confidence interval on the basis of mean is ( 21.7393  ;   22.0257)
Step-by-step 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)
 
        
             
        
        
        
Lets solve all of these:-
#1
√361 = 361 · 2
         
         ?
√361 = 361 · 2
√361 = 19
361 · 2 = 722
19 ≠ 722
So this equation is not true
#2:-
√361 = 19²
         ?
√361 = 19²
√361= 19
19² = 19 · 19 = 361
19 ≠ 361
So this equation is not true
√361 = 361 ÷ 2 
         ?
√361 = 361 ÷ 2 
√361 = 19
361 ÷ 2 = 180.5
√361 ≠ 361 ÷ 2 
So this equation is not true
√361 = √19²
√361 = 19
√19² = 19
19 = 19
SO the last one is right. Hope I helped ya!! xD
        
             
        
        
        
The answer is 4) as it is more than 40 degrees
        
             
        
        
        
~54: 1,2,3,6,9,27~
~2,754:1,2,3,6,9,17,18,27,34,51,54,81,102,153,162,
306,459, 918,1377,2754~
~27: 1,3,9,27~
GCF: 27
Your answer would be for the GCF would be 27