Finding initial investment and interest earned with simple interest

[lil.l3b91]

Homework Statement

Michael's investment in his savings account matured to $4,106.32 at the end of 165 days. If the account was earning simple interest at a rate of 4.80% p.a., answer the following.
a. What was Michael's initial investment?

Round to the nearest cent
b. How much interest did Michael earn?

Round to the nearest cent

Homework Equations

p=s(1+rt) ?
I=prt

The Attempt at a Solution

s=4,106.32
t=165/365
r=0.048

s=4,106.32(1+0.048*165/365)

 

[Chestermiller]

It should be divided, not multiplied.

 

[vela]

Homework Statement

Michael's investment in his savings account matured to $4,106.32 at the end of 165 days. If the account was earning simple interest at a rate of 4.80% p.a., answer the following.
a. What was Michael's initial investment?

Round to the nearest cent
b. How much interest did Michael earn?

Round to the nearest cent

Homework Equations

p=s(1+rt) ?
I=prt

The Attempt at a Solution

s=4,106.32
t=165/365
r=0.048

s=4,106.32(1+0.048*165/365)

You've mixed up $p$ and $s$. $p$ is the final value of the investment, and $s$ is the amount initially invested. Make sure you understand what each variable in a formula represents instead of plugging numbers in willy-nilly.