Answer:
b=9,a=12
Step-by-step explanation:
I solved by substitution:
b = 3/4a  ---> plug this into the other equation
a + b = 21   is now    a + 3/4a = 21
Reduce: 7/4a = 21
a = 12
Now solve for b:
b=3/4a is now b=3/4(12)
b=9
 
        
                    
             
        
        
        
X intercept: (- 1/7, 0)
Y intercept: (0, 1/4)
        
             
        
        
        
Answer:
Are you supposed to change decimals to fractions and fractions to decimals? 
If yes, 
0.5 = 1/2
11/4 = 2.75
0.25 = 1/4
3/8 = 0.375
 
        
             
        
        
        
Answer:
It is an unusual result contradicting the national survey.
Step-by-step explanation:
National survey showed 44% of college students who drink.
The professor's survey showed that 96/244 = 39% drink.
The professor's survey deviated from the national survey is 5% (44% - 39%) representing about 0.25% (5% squared) variance.
Standard deviation is the spread of a set of numbers from their mean.  In other words, it measures how far an observed value is from the mean. It can be calculated by getting the square root of the variance.