Answer: 7.2 months
Step-by-step explanation:
Hi, to answer this question we have to substitute f(x) =500 in the equation given:
f(x) = 100(1.25)^x
500= 100(1.25)^x
Solving for x (number of months)
500/100 = 1.25^x
5 = 1.25^x
log 5 =log 1.25^x
log 5 =x (log 1.25)
log 5 /log 1.25 =x
x = 7.2 months
Feel free to ask for more if needed or if you did not understand something.