A woman invests $4,250 in government bonds for 7 years at 9% simple interest.
a) Calculate the total interest she receives for 7 years.
b) Calculate the sum that must be invested in bonds to obtain a total interest of $3 500 in 7 years.

Respuesta :

The equation for the total is T = 4250 *1.07^7

She starts off with 4250(100%). After 1 year she would have 107%. After 2 years, it’s that 107% times another 107% or 1.06^2 and so on.

A) $6824.57

“x amount of money she starts with times 7% interest over 7 years, minus the amount of money she started with equals 3500 in interest”

(x * 1.07^7) - x = 3500

x * 1.60578147648 - x = 3500

1.60578147648x - x = 3500

0.60578147648x = 3500

x = 5777.66098154

B) $5777.66