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At what rate of interest?

  • Thread starter Math10
  • Start date
  • #1
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Homework Statement


At what rate of interest, compounded continuously, will a bank deposit double in value in 8 years?

Homework Equations


None.

The Attempt at a Solution


Q0e8r=2Q0
e8r=2
8r=ln(2)
r=ln(2)/8
But the answer is (25/2)ln(2)%. How do I get the answer from there?
 

Answers and Replies

  • #2
Ray Vickson
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Homework Statement


At what rate of interest, compounded continuously, will a bank deposit double in value in 8 years?

Homework Equations


None.

The Attempt at a Solution


Q0e8r=2Q0
e8r=2
8r=ln(2)
r=ln(2)/8
But the answer is (25/2)ln(2)%. How do I get the answer from there?
Be careful about units.
 
  • #3
301
0
Thank you for reminding me about units. I got it! Thanks a lot!
 
  • #4
1,353
336
MY father pointed out that doubling of principal occurs - approx 72 / Rate ...... while not accurate enough for an answer, a quick check of you are in the ball park... 9 vs 8.66
 

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