Question

Lucy earned $400 and $550 in interest the last 2 years. Describe the average interest she should earn in each of the next 3

years so that her total earnings over the 5-year period are at least $2300.
A)
She must average $450 per year.
B)
She must average $900 per year.
c)
She must average $1350 per year.
D)
She must average $1800 per year.

Answer 1

A) She must average $450 per year.

Explanation:

Given:

Lucy earned $400 and $550 in interest the last 2 years.

To Find:

Average interest she should earn in each of the next 3 years so that her total earnings over the 5-year period are at least $2300.

Solution:

Let the average interest be x

Let us use inequality to represent the situation stated,

then after 5 years

`400 + 550 +3x \geq 2300`

solving the equation,

`950+3x \geq 2300`

`950+3x \geq 2300`

`3x \geq 2300 - 950`

`3x \geq 1350`

`x \geq(1350)/(3)`

`x \geq 450`

Thus the average interest she should earn in each of the next 3 years so that her total earnings over the 5-year period are at least $2300 is $450 per year.