Answer:
The 95% confidence interval for the true proportion of bottlenose dolphin signature whistles that are type a whistles is (0.4687, 0.6123).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of  , and a confidence level of
, and a confidence level of  , we have the following confidence interval of proportions.
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of  .
.
For this problem, we have that:

95% confidence level
So  , z is the value of Z that has a pvalue of
, z is the value of Z that has a pvalue of  , so
, so  .
. 
The lower limit of this interval is:

The upper limit of this interval is:

The 95% confidence interval for the true proportion of bottlenose dolphin signature whistles that are type a whistles is (0.4687, 0.6123).
 
        
             
        
        
        
Answer:
B 
Step-by-step explanation:
 9 multiple 2m = 18m
9 multiple 5n = 45n
9 multiple 10= 90 
 
        
                    
             
        
        
        
Answer:
Seth has 21 nickels
Step-by-step explanation:
Let n represent the number of nickels. Since Seth has 8 more nickels than dimes, then (n-8) is the number dimes. 
Nickel is worth 5 cents and dime is worth 10 cents.  Thus, n nickels are worth 5n cents and (n-8) dimes are worth 10(n-8) cents. The total value of Seth's coins is $2.35 that is 235 cents, then

Solve this equation:

 
        
             
        
        
        
{3x+2y=4    /*5
{4x+5y=17    /*(-2)
{15x+10y=20
<u>{-8x-10y=-34        </u>(+)
<em>7x=-14</em><em />
<em>x=-2</em>
15x+10y=20
15*(-2)+10y=20
-30+10y=20
10y=50
<em>y=5</em>
        
                    
             
        
        
        
Answer:
your answer should be x = -3