Answer:
The length of the circumference is  or
  or 
Step-by-step explanation:
<u><em>The question in English is</em></u>
On a court, the central circumference will be painted, which has a diameter of 5 m. What is the length of the circumference?
we know that
The circumference of a circle is given by the formula

we have

substitute

This is the exact value
assume


 
        
             
        
        
        
Answer:
1 : 20 20 students for every 1 teacher
Step-by-step explanation:
divide both sides by 12
 
        
             
        
        
        
<span>At least 75% of the data will fall within 2 standard deviations of the mean.
This is tricky problem. Usually when you're dealing with standard deviation, you have a bell curve, or something close to a bell curve and for such a data distribution, there will be approximately 95% of the data within 2 standard deviations of the mean. But if you don't know that you have a bell curve, you have to fall back to Chebyshev’s Theorem, which states that at least 75% of the data points will fall within 2 standard deviations of the mean for any set of numbers.</span>
        
                    
             
        
        
        
The Mean = (135 + 71 + 69 + 80 + 158 + 152 + 161 + 96 + 122 + 118 + 87 + 85 ) : 12 = 111.166
The smallest value : 69
The greatest value : 161
s² = ∑( x i - x )² / ( n - 1 )
s² = ( 568.274 + 1613.3 + 1777.97 + 971.32 + 2193.42 + 1667.4 + +2483.42 + 230 + 117.38 + 46.7 + 584 + 684.66 )  : 11
s² = 1176.1676
s = √s² = √1176.1676
s ( Standard deviation ) = 34.295
All the values fall within 2 standard deviations:
 x (Mean) - 2 s and  x + 2 s 
 
        
                    
             
        
        
        
Answer:

Step-by-step explanation:
The exponential function that decrease by 15% every time x increases by 1 is given by:

We simplify the parenthesis to get:

Therefore the decrease by 15% every time x increases by 1 is 

The second choice is correct.