+956 If you invested money into an account that pays 9%/a compounded weekly, how many years would it take for your deposit to double?
+118677 If you invested money into an account that pays 9%/a compounded weekly, how many years would it take for your deposit to double?
\(2A=A(1+\frac{0.09}{52})^{n}\\ 2=(1+\frac{0.09}{52})^{n}\\ log2=log(1+\frac{0.09}{52})^{n}\\ log2=nlog(1+\frac{0.09}{52})\\ n=log2\div log(1+\frac{0.09}{52})\\\)
log(2)/log(1+0.09/52 = 400.831511360387616 weeks
400.831511360387616/52 = 7.708298295392069538
7.7 years
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check
1*(1+0.09/52)^400.83 = 1.9999947728968765
+956 Oh never mind, there is 52 weeks in a year :D
Also how did the A go away?
+118677 The A stands for any Amount.
There is 1 of them at the start and there must be 2 of them at the end.
I just divided both sides by A to get rid of the A.
I could just have easily have said there was $1 at the beginning and $2 at the end and then I would not have needed the A at all. 
