One of the few things to memorize for the Regents is the formula for compound interest:
A = P(1 + r)^t
A is the account balance or amount
P is the principal or initial amount = 3000
r is the rate 4.2 % we need to convert this to a decimal

t is time

so the equation is:
A = 3000 (1 + .042)^t     or it can be written as:  A = 3000 (1.042)^t
That’s it — just writing this equation is 2 points!!

Please visit this blog post for a related multiple choice item from Jan 2016:

Get the Math and Get the Points Jan 2016 CC Alg I Regents #8