Answer:
The inicial deposit is $7700
Explanation:
The equation that describes a compound interest is:
P = Po*(1+(r/n))^(t*n)
Where P is the final value, Po is the inicial value, r is the rate, t is the amount of time and n is defined by the period that the interest is compounded
As in our case the interest is compounded quarterly, we have n = 4.
We also have that P = 10,891.31, r = 2.9% = 0.029 and t = 12
Then, we can calculate for Po:
10891.31 = Po * (1 + 0.029/4)^(12*4)
10891.31 = Po * (1 + 0.00725)^(48)
10891.31 = Po * 1.414455
Po = 10891.31 / 1.414455 = 7700
So the inicial deposit is $7700