On january 1, 1970, lois deposited $1950 into a savings account paying 6.6% interest, compounded semiannually. if she hasn't made any additional deposits or withdrawals since then, and if the interest rate has stayed the same, in what year did her balance hit $3900, according to the rule of 72? a. 1979 b. 1981 c. 1982 d. 1980

D. 1980.      

Step-by-step explanation:

We have been given that on January 1, 1970, Lois deposited $1950 into a savings account paying 6.6% interest, compounded semiannually. We are asked to find the year in which Lois's balance hit $3900, according to the rule of 72.

The rule of 72 states the number of years it will take an investment to be double.

Since $3900 is twice the amount $1950, so we will divide 72 by our given interest rate to find the number of years it will take to double the given amount.

Since the amount will be double in 11th year, so 11th year after January 1, 1970 will be 1980.

Therefore, in year 1980 Lois amount will be double and option D is the correct choice.