I don't think it's a math problem specifically I believe it was something to do with how they calculate the apy perhaps how often they compound.
They figure the APY correctly. My mistake was I thought APY was the same as APR, they are not. The formula I posted calculates the APR and I need it to calculate the APY. Probably better to ask in the excel thread now.
APY calculates with compounding.
APR does not use compounding.