High School

Initially, there were only 197 weeds at a park. The weeds grew at a rate of [tex]25\%[/tex] each week. The following function represents the weekly weed growth:

[tex] f(x) = 197(1.25)^x [/tex]

Rewrite the function to show how quickly the weeds grow each day and calculate this rate as a percentage.

A. [tex] f(x) = 197(1.25)^{7x} [/tex] : grows at a rate of approximately [tex]2.5\%[/tex] daily

B. [tex] f(x) = 197\left(1.25^7\right)^x [/tex] : grows at a rate of approximately [tex]4.77\%[/tex] daily

C. [tex] f(x) = 197(1.03)^x [/tex] : grows at a rate of approximately [tex]0.3\%[/tex] daily

D. [tex] f(x) = 197(1.03)^{7x} [/tex] : grows at a rate of approximately [tex]3\%[/tex] daily

Answer :

To determine how quickly the weeds grow each day as a percentage, we start by considering the initial situation.

1. Initial Information:
- Initially, there are 197 weeds.
- The weeds grow at a rate of 25% per week.

2. Weekly Growth Function:
- The weekly growth of weeds is represented by the function [tex]\( f(x) = 197(1.25)^x \)[/tex], where [tex]\( x \)[/tex] is the number of weeks.

3. Transition to Daily Growth:
- We need to express the growth rate on a daily basis. Since there are 7 days in a week, the daily growth function can be derived by taking the 7th root of the weekly growth rate:
[tex]\[
(1.25)^{1/7}
\][/tex]

4. Resulting Daily Growth:
- When calculated, the daily growth rate is approximately 1.03239. This means that each day, the number of weeds is multiplied by about 1.03239.

5. Daily Growth Rate as a Percentage:
- To convert the daily growth factor into a percentage increase, subtract 1 (to find just the growth part beyond the original amount) and then multiply by 100:
[tex]\[
(1.03239 - 1) \times 100 \approx 3.24\%
\][/tex]
- Therefore, the weeds grow at an approximate rate of 3.24% each day.

This step-by-step approach explains how the function representing weekly growth was adjusted to find the rate of daily growth and ultimately expressed as a percentage increase. The correct function that matches this daily growth rate is [tex]\( f(x) = 197(1.03239)^x \)[/tex], which indicates the weeds grow approximately at a rate of 3.24% daily.