Marshall earned some money doing odd jobs last summer and put it in a savings account that earns 7% interest compounded quarterly. After 10 years, there is 400.00 in the account. How much did Marshall earn doing odd jobs?

Solution

M a rs ha ll e a r n e d so m e m o n ey d o in g o dd j o b s l a s t s u mm er an d p u t i t in a s a v in g s a cco u n t t ha t e a r n s 7% in t eres t co m p o u n d e d q u a r t er l y . A f t er 10 ye a rs, t h ere i s 400.00 in t h e a cco u n t . Ho w m u c h d i d M a rs ha ll e a r n d o in g o dd j o b s ?

Principal : 199.84

Solution steps

Translate the problem into an equation:

400 = P (1 + \frac{0.07}{4})^{4 \cdot 10}

Solve for

P, 400 = P (1 + \frac{0.07}{4})^{4 \cdot 10} : P = 199.84

Principal : 199.84