Here's the given:
P=$400
i=7.5%
A=$8500
The formula used for this problem is:
A = P(1+i)^t
Manipulating the equation to arrive at t, we have:
t = ln(A/P) / ln(1+i)
Plugging in values:
t = ln($8500/$400) / ln(1+0.075)
t = 42.26 years
The answer to this question is "you gained profit". The amount of money you gain from selling the stocks now is higher compared to the amount you spent a year ago. The amount you gain from the shares is ($62.25) x 723 = $45006.75. The amount you spent last year is ($47.75) x 723 = $34523.25. The difference between the values is $10483.47. Thus, you gained $10483.47.
