Answer:
0.04746
Step-by-step explanation:
To answer this one needs to find the area under the standard normal curve to the left of 5 minutes when the mean is 4 minutes and the std. dev. is 0.6 minutes.  Either use a table of z-scores or a calculator with probability distribution functions.
In this case I will use my old Texas Instruments TI-83 calculator.  I select the normalcdf( function and type in the following arguments:  :
normalcdf(-100, 5, 4, 0.6).  The result is 0.952.  This is the area under the curve to the left of x = 5.  But we are interested in finding the probability that a conversation lasts longer than 5 minutes.  To find this, subtract 0.952 from 1.000:   0.048.  This is the area under the curve to the RIGHT of x = 5.
This 0.048 is closest to the first answer choice:  0.04746. 
 
        
             
        
        
        
Answer:
x=2
Step-by-step explanation:
combine like terms to get 15x=30. divide by 15 on both sides to get x=2
 
        
                    
             
        
        
        
Answer:
Inverse Function: f^-1(x) = 9/4x + 9
Step-by-step explanation:
To find  the inverse function we can interchange the position of the variables x and y, and then solve for y;
y = 4/9x - 4 => x = 4/9y - 4,
x = 4/9y - 4,
4/9y = x + 4,
y = 9/4x + 9/4(4),
y = 9/4x + 9/ f^-1(x) = 9/4x + 9
 
        
             
        
        
        
We have the following function:

So if we graph this function we will get the Figure below. Thus, let's study both the equation and the graph to get some conclusions. Therefore, we can assure these statements:
First. The function is defined only for 

 as shown in the Figure. This is also true because of 

 where 

 must be greater (or equal) than zero.
Second. The range of the function are the values of 

.
Third. If 

 creases then 

 always creases, too. 
 
        
        
        
Hi,
h = 2 a/b so our answer would be 6. The height of the triangle is 6.
Have a great day!