Erin earned some money doing odd jobs last summer and put it in a savings account that earns 12% interest compounded quarterly. After 2 years, there is 100.00 in the account. How much did Erin earn doing odd jobs?Round your answer to the nearest cent.

Solution

E r in 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 12% 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 2 ye a rs, t h ere i s 100.00 in t h e a cco u n t . Ho w m u c h d i d E r in e a r n d o in g o dd j o b s ? R o u n d yo u r an s w er t o t h e n e a res t ce n t .

Principal : 78.94

Solution steps

Translate the problem into an equation:

100 = P (1 + \frac{0.12}{4})^{4 \cdot 2}

Solve for

P, 100 = P (1 + \frac{0.12}{4})^{4 \cdot 2} : P = 78.94

Principal : 78.94