Question

Brenna O'Connor earned $120 in simple interest in 9 months at an annual interest rate of 8%. How much money did she invest?

Answer 1

Brenna O'Connor invested $2000 to earn $120 in simple interest over 9 months at an annual interest rate of 8%.

Step-by-step explanation:

To calculate how much money Brenna O'Connor invested to earn $120 in simple interest over 9 months with an annual interest rate of 8%, we can use the simple interest formula:

I = P × r × t

where:

I is the interest earned,

P is the principal amount (initial investment),

r is the annual interest rate (as a decimal), and

t is the time the money is invested (in years).

We're given that Brenna's interest (I) is $120, the annual interest rate (r) is 8% (or 0.08 as a decimal), and the time (t) is 9 months, which is ⅔ or 0.75 years.

Plugging these values into the formula, we get:

120 = P × 0.08 × 0.75

To find P, we divide both sides of the equation by (0.08 × 0.75):

P = 120 / (0.08 × 0.75)

P = $2000

Therefore, Brenna invested $2000 to earn $120 in simple interest.

Answer 2

Brenna O'Connor invested $2000.

Step-by-step explanation:

To find the amount of money Brenna O'Connor invested, we can use the formula:

Simple Interest = (Principal) x (Rate) x (Time)

$120 = Principal x 0.08 x (9/12)

To solve for the Principal, we can rearrange the formula:

Principal = $120 / (0.08 x (9/12))

Principal = $120 / 0.06

Principal = $2000

Therefore, Brenna O'Connor invested $2000.