Help what am I doing wrong

Question

anonymous · Answer

Kevin made contributions to a Roth IRA over the course of 40 working years. His contributions averaged $3,000 annually. Kevin was in the 25% tax bracket during his working years. The average annual rate of return on the account was 7%. Upon retirement, Kevin stopped working and making Roth IRA contributions. Instead, he started living on withdrawals from the retirement account. At this point, Kevin dropped into the 15% tax bracket. Factoring in taxes, what is the effective value of Kevin’s Roth IRA at retirement? Assume annual compounding.

anonymous · Answer

FVOA=C x (1+i)^nt - 1/ i

I did 3000 x (1+0.07)^40 - 1/0.07
I keep getting 598905.33596601208854

anonymous · Answer

but that isn't one of my choices