Answer:
The hourly decay rate is of 1.25%, so the hourly rate of change is of -1.25%.
The function to represent the mass of the sample after t days is 
Step-by-step explanation:
Exponential equation of decay:
The exponential equation for the amount of a substance is given by:

In which A(0) is the initial amount and r is the decay rate, as a decimal.
Hourly rate of change:
Decreases 26% by day. A day has 24 hours. This means that  ; We use this to find r.
; We use this to find r.



![\sqrt[24]{(1-r)^{24}} = \sqrt[24]{0.74}](https://tex.z-dn.net/?f=%5Csqrt%5B24%5D%7B%281-r%29%5E%7B24%7D%7D%20%3D%20%5Csqrt%5B24%5D%7B0.74%7D)



The hourly decay rate is of 1.25%, so the hourly rate of change is of -1.25%.
Starts out with 810 grams of Element X
This means that 
Element X is a radioactive isotope such that its mass decreases by 26% every day. 
This means that we use, for this equation, r = 0.26.
The equation is:



The function to represent the mass of the sample after t days is 
 
        
             
        
        
        
Answer:
7598.80 
Step-by-step explanation:
V=πr^2h
= 3.14 * 11^2 * 20
= 2420π or 7598.80 
 
        
                    
             
        
        
        
<span>Answer 61 73-66= 7 21-13 = 8 ?? -52= 9 20-10 = 10 ??=61</span>
        
             
        
        
        
Answer:
300 dollars
Step-by-step explanation:
Let the original amount = x
x - 2/5x  was what his mother's share looked.
5/5 x - 2/5 x
3/5x is what is left.
3/5 x - 1/4 * 3/5 x - 2/3x * 3/5 = his sister's share and his brothers
3/5x - 1/4*3/5 x - 2/3 * 3/5 = 15
3/5x * (1 - 1/4 - 2/3) = 15
3/5 x 5/60 = 15
15 / 300 * x = 15
1/20  x = 15
x = 15 * 20
x = 300
 
        
             
        
        
        
Answer:
the second one
Step-by-step explanation: