Answer:
$800.
Explanation:
We have been given that Gene's deposit earns 2.8 percent simple annual interest. At the end of the year, the interest that is earned is $22.40. We are asked to find the amount of original deposit.
To find the original amount of deposit, we use simple interest formula:
, where,
I = Amount of interest,
P = Principal amount,
r = Annual interest rate in decimal form,
t = Time in years.
Let us convert our given interest rate in decimal form.
![2.8\%=(2.8)/(100)=0.028](https://img.qammunity.org/2019/formulas/mathematics/middle-school/etq20xmi6mmieunk2b0g1a592ppswv4m1u.png)
Upon substituting our given values in above formula, we will get:
![\$22.40=P*0.028*1](https://img.qammunity.org/2019/formulas/mathematics/middle-school/oo04ajodx0ei2ns2avu0yfcpg05w25pl3q.png)
![\$22.40=P*0.028](https://img.qammunity.org/2019/formulas/mathematics/middle-school/vkjd4tgsyf5nt75vjgqmrgfsei57wv8w4p.png)
![(\$22.40)/(0.028)=(P*0.028)/(0.028)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/oduspaf687ez5kr2pxdzvmjtbt0r63rygx.png)
![\$800=P](https://img.qammunity.org/2019/formulas/mathematics/middle-school/1x0mmwk91zf76ajgw20sxkmknqjetwwblq.png)
Therefore, the amount of original deposit was $800.