The height of the blue spruce was 45.
We find the mean by adding all of the data points and dividing by the number of data points.  We will add the unknown value x and change the number we're dividing by to 7:
(160+320+100+110+200+220+x)/7 = 165
(1110+x)/7 = 165
Multiply both sides by 7:
1110 + x = 1155
Subtract 1110 from both sides:
x = 45
        
                    
             
        
        
        
One form of the relation of inverse variation is y = k/x.
first step:  Find the value of k:    Taking the values x=5 and y = 4, 4=k/5, or k=20.  Then,   y = 20/x.
Next:  Let y = 7 and find the corresp. value of x:  7=20/x, or 7x=20, or
x = 20/7    (answer) 
        
                    
             
        
        
        
A)
total of balls = 8+6+10= 24 balls 
3/24= .125 and it is 12.5 % that one of the orange balls is 5 because it is an odd number.
B) 
4/24 =.167 0r 16.7% that of the gray balls is numbered 8.