Math! . really don't understand this one!

little miss buffet takes all the money from her piggy bank and puts it into a savings account at her local bank. the bank promises an annual interest rate of 3% on the balance, compounded semiannually. how much will she have after one year if her initial deposit was $400?

$529.00

$412.17

$2,500.00

412.09

The table below shows the approximate masses of a dust particle and a grain of pollen. dust particle 0.000000778 g grain of pollen 0.00000000155 g the mass of a dust particle can be estimated and written in the form a × 10^b, where a = 8 and b = the mass of a grain of pollen can be estimated and written in the form a × 10^b, where a = 2 and b = based on the estimates, the mass of a dust particle is approximately blank times larger than the mass of a grain of pollen.