High School

There were 124 pairs of windshield wipers sold at an auto parts store in April. Since then, windshield wiper sales have decreased at a rate of [tex]$4.5 \%$[/tex] per month. At this rate, which function can be used to determine the number of windshield wipers sold [tex]$m$[/tex] months after April?

A. [tex]w(m) = 124(0.045)^m[/tex]

B. [tex]w(m) = 124(1.45)^m[/tex]

C. [tex]w(m) = 124(0.955)^m[/tex]

D. [tex]w(m) = 124(1.045)^m[/tex]

Answer :

To solve this problem, let's break down the steps:

1. Understand the Decrease in Sales:
The problem states that the windshield wiper sales decrease at a rate of 4.5% per month. This means that each month, the store sells 4.5% less than the previous month.

2. Calculate the Remaining Percentage Sold Each Month:
If sales decrease by 4.5%, then 100% - 4.5% = 95.5% of the previous month's sales are sold each month. This can be represented as a decimal: 0.955.

3. Determine the Exponential Function:
We know that initially, 124 pairs of windshield wipers were sold in April. We're looking for a function that shows the decrease over multiple months.

4. Set Up the Function:
Since the sales decrease is exponential (a consistent percentage decrease each month), we use an exponential decay function. The number of windshield wipers sold [tex]\( m \)[/tex] months after April can be represented by the function:
[tex]\[
w(m) = 124 \times (0.955)^m
\][/tex]
Here, 124 is the initial number of sales, 0.955 is the remaining sales rate after each month, and [tex]\( m \)[/tex] is the number of months after April.

This procedure results in the function:
[tex]\[ w(m) = 124(0.955)^m \][/tex]

This function correctly models the continuous monthly decrease in sales, reflecting the initial condition and the monthly percentage decrease.