how many years will it take for a debt to double at 15% p.a compound interest?

Question

the p.a is per year. the formula is C*R*N/100. but I don't know how to do this

Answer 1

X*(1.15)^t = 2X

 

(1.15)^t = 2x/x = 2

 

 

log (1.15)^t = log(2)

 

 t * log(1.15) = log(2)

 

t = log(2)/log(1.15) = 4.9595

 

Almost 5 years. 

Check( 1.15)^5 = 2.0113571875 <--- YES!!!