To calculate the final amount of the acount that compounds quarterly you have to use the following formula:
Where
A is the accrued amount
P is the principal amount
r is the interest rate, expressed as a decimal value
t is the time period
n is the number of compound periods per time unit. This savings account compounds quarterly, this means, 4 times per year
P=$400.00
r=4/100=0.04
t= 4 years
n=4*4=16
The amount at the end of the 4 year period will be $469.31