How Old is Lee Based on the Given Mathematical Problem?

  • Context: MHB 
  • Thread starter Thread starter mathdad
  • Start date Start date
  • Tags Tags
    Age
Click For Summary

Discussion Overview

The discussion centers around a mathematical problem involving the ages of Lee and her sisters. Participants are attempting to set up equations based on the relationships described in the problem, which involves determining Lee's age given the ages of her older and younger sisters. The scope includes mathematical reasoning and problem-solving related to age relationships.

Discussion Character

  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant, RTCNTC, initially sets up an equation but arrives at a fractional age for Lee, which they question as incorrect.
  • Another participant points out that RTCNTC's representation of Lee's younger sister's age is incorrect, suggesting that it should be represented as \(x - 3\) instead of \((2x + 1) - 3\), leading to a revised equation that yields \(x = 7\).
  • A later reply reiterates the correction regarding the younger sister's age and confirms that Lee's age is \(7\) based on the corrected equation.
  • Some participants express their interpretation of the problem, emphasizing that the statement about Lee's younger sister being three years younger than her is clear and supports the conclusion that Lee is \(7\) years old.

Areas of Agreement / Disagreement

There is a general agreement among participants that Lee's age is \(7\) years, but there is some contention regarding the initial setup of the equations and the interpretation of the relationships between the ages.

Contextual Notes

The discussion highlights potential confusion in the initial equation setup and the importance of accurately defining variables. There are unresolved aspects regarding the clarity of the problem statement and how it may lead to different interpretations.

mathdad
Messages
1,280
Reaction score
0
Lee has an older sister and a younger sister. Her older sister is one year more than twice Lee's age. Lee's younger sister is three years younger than she is. The sum of their three ages is 26. Find Lee's age?

My equation set up is

x + (2x + 1) + (2x + 1) - 3 = 26

This equation yields a fraction answer which is not possible in terms of age.

My answer is 27/5 as Lee's age.This cannot be right. What do you say?
 
Mathematics news on Phys.org
Hi RTCNTC,

It's important to write down what your variables represent. If $x$ represents Lee's age, then $x - 3$, not $(2x + 1) - 3$, represents the age of Lee's younger sister. The equation is then

$$x + (2x + 1) + (x - 3) = 26$$

yielding $x = 7$.
 
Euge said:
Hi RTCNTC,

It's important to write down what your variables represent. If $x$ represents Lee's age, then $x - 3$, not $(2x + 1) - 3$, represents the age of Lee's younger sister. The equation is then

$$x + (2x + 1) + (x - 3) = 26$$

yielding $x = 7$.

There is a typo in the application. Lee's younger sister is 3 years younger than him not the older sister. I also got x = 7. So, Lee is 7 years old.
 
My interpretation of the original problem is that "Lee" is a girl and the sentence "Lee's younger sister is three years younger than she is." means that the younger sister is three years younger than Lee.[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main]2[FONT=MathJax_Main])[FONT=MathJax_Main]⊂[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main])[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main]2[FONT=MathJax_Main])[FONT=MathJax_Main]⊂[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main])[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main]2[FONT=MathJax_Main])[FONT=MathJax_Main]⊂[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main])[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main]2[FONT=MathJax_Main])[FONT=MathJax_Main]⊂[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main])
 
HallsofIvy said:
My interpretation of the original problem is that "Lee" is a girl and the sentence "Lee's younger sister is three years younger than she is." means that the younger sister is three years younger than Lee.[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main]2[FONT=MathJax_Main])[FONT=MathJax_Main]⊂[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main])[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main]2[FONT=MathJax_Main])[FONT=MathJax_Main]⊂[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main])[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main]2[FONT=MathJax_Main])[FONT=MathJax_Main]⊂[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main])[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main]2[FONT=MathJax_Main])[FONT=MathJax_Main]⊂[FONT=MathJax_Math]R[FONT=MathJax_Main]([FONT=MathJax_Math]T[FONT=MathJax_Main])
Well, the answer is x = 7.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
6
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K