Question 1024729:  Please help me with these problems. Thanks and show all work
 
1. A bank features a savings account that has an annual percentage rate of r=4.7 
% with interest compounded quarterly. Zach deposits $3,500 into the account. 
 
The account balance can be modeled by the exponential formula S(t)=P(1+rn)nt 
, where S is the future value, P is the present value,r is the annual percentage rate, n is the number of times each year that the interest is compounded, and t is the time in years. 
 
 (A) What values should be used for P, r, and n?P=, r=, n= 
  
 (B) How much money will Zach have in the account in 8 years?  
 Answer = $ .     Round answer to the nearest penny
 
 
2.If 15700 dollars is invested at an interest rate of 8 percent per year, find the value of the investment at the end of 5 years for the following compounding methods.  
 (a) Annual:  
 Your answer is       
 (b) Semiannual:  
 Your answer is       
 (c) Monthly:  
 Your answer is       
 (d) Daily:  
 Your answer is      
 
 
3.  An unknown radioactive element decays into non-radioactive substances. In 420 days the radioactivity of a sample decreases by 26 percent. 
 
 (a) What is the half-life of the element?  
 half-life:      (days) 
 
 (b) How long will it take for a sample of 100 mg to decay to 75 mg?  
 time needed 
 Answer by solver91311(24713)      (Show Source): 
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