A $50,000 investment earns 18% annually. If B represents the balance and t represents the number of years, determine an expression that gives the account balance, B, after t years. Also, determine an equivalent expression that displays the effective monthly interest rate.

Using the compound interest formula;

FV=P (1+r/100) ^t

FV is the future value

P is the principle

r is the rate

t is the time

the formula that gives the account balance after t years will be:

FV=50000 (1+18/100) ^t

FV=50000 (1.18) ^t

The formula for effective monthly interest rate will be:

monthly interest rate = (annual rate) / (number of months)

annual rate=18%

number of months in a year=12 months

rate=18/12=1.5%