Question 1106244:  Solve for t algebraically. Round answers to the nearest hundredth.
 
100(1/2)^t/5 = 20
 
So,I know you divide the whole equation by 100,which leaves me with,
 
(1/2)^t/5 = 1/5
 
Then I take the log of each side, my book tells me to use ln, so I end up with
 
ln(1/2)^t/5 = ln 1/5
 
Move t/5 over, now I get
 
t/5 ln(1/2) = ln 1/5
 
Multiply everything by 5
 
t ln(1/2) = 5 ln 1/5
 
Is that correct? I've tried everything I can think of, yet I still get the wrong answer. Would you please help me? 
 Answer by Alan3354(69443)      (Show Source): 
You can  put this solution on YOUR website! Solve for t algebraically. Round answers to the nearest hundredth.
 
100(1/2)^t/5 = 20
 
So,I know you divide the whole equation by 100,which leaves me with,
 
(1/2)^t/5 = 1/5
 
Then I take the log of each side, my book tells me to use ln, so I end up with
 
ln((1/2)^t/5) = ln 1/5
 
Move t/5 over, now I get
 
t/5 ln(1/2) = ln(1/5) 
======================
 
t/5 = ln(1/5)/ln(1/2)
 
Multiply everything by 5 
t = 5ln(1/5)/ln(1/2) 
Then use a calculator. 
t =~ 11.61
 
 
 
 
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