Solving a Word Problem: Algae Increase by Factor of 4 Every 60 Days

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Homework Help Overview

The problem involves understanding the growth of algae, which increases by a factor of 4 every 60 days. The original poster seeks to determine how many days it takes for the algae to double in size and how many days ago it was half its current size.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to solve the first question by calculating that it takes 30 days for the algae to double in size. They express confusion regarding the second question about how many days ago the algae was half its current size.
  • Some participants suggest looking backwards from the current size to determine when the algae was half its size, referencing the growth factor and time intervals.
  • One participant attempts a calculation to find the time elapsed since the algae was half its current size, leading to a proposed answer of 7.5 days ago, but they question its correctness.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the second question and attempting calculations based on the growth factor. There is no explicit consensus yet, but some guidance has been provided regarding the approach to the second part of the problem.

Contextual Notes

Participants are working within the constraints of the problem as stated, focusing on the growth factor and time intervals without additional information or context about the algae's growth beyond what is provided in the problem statement.

Jimmy84
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Homework Statement


I just translated this word problem:

The zone of a alga increases every 2 month about the factor 4. How many days does the alga needs to increse into the double? How many days ago has the alga been the half?


Homework Equations





The Attempt at a Solution




1.) The first question states

The algae increases by a factor of 4 every 60 days. how many "days" does the alga needs to increse into the double?


So I got 4x = 60 multiplyed 2

x = 30 days


2.) I don't understand the second question.

How many days ago has the alga been the half?

I would appreciate some help, thanks.
 
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The second part wants you to look backwards. The algae is size x at the moment. 30 days from now, you found that the algae would be 2x in size. Using the fact that the algae will increase by a factor of 4 in size over 60 days, how many days ago was the algae 0.5x in size?
 
singular said:
The second part wants you to look backwards. The algae is size x at the moment. 30 days from now, you found that the algae would be 2x in size. Using the fact that the algae will increase by a factor of 4 in size over 60 days, how many days ago was the algae 0.5x in size?

I tryed 2x = 30 multiplyed by 0.5

= 7.5 days ago is that right?

thanks
 
Jimmy84 said:
I tryed 2x = 30 multiplyed by 0.5

= 7.5 days ago is that right?

thanks

If the algae increases by a factor of 4 every 60 days, then 60 days prior to the algae being size x (at present), the algae will be 0.25x. Starting from 0.25x, how long will it take for the algae to increase to 0.5x?
 

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