My kid's teacher don't know no math!

[ohchaucer 1443]

Despite being told there would be no math, I need some help.  My daughter is in the third grade and each week they have a bonus "math challenge" that hits on logic problems, algebra, etc.   Now, I'm not a math guy, but I retain enough from high school to be dangerous.  And I also know that out of 20 or so questions this year, on 5 or 6, her math teacher has fundamentally either written a long form question ambiguously such that there are multiple correct answers and/or has just flat out not graded the correct answer.  

Two examples are below if you'd care to solve them with me and we'll just see how smart she is!

1. The sum of two numbers is 30.  Three times the first plus twice the second number is 72.  Find the numbers.

2. The sum of two numbers is 41. One number is one more than twice the other.  Find the others. 

What say the Surly? 

[High Plains Drifter 11024]

 

#1:  two numbers are 12 and 18

[Jerry Callo 8695]

1 minute ago, High Plains Drifter said:

 

#1:  two numbers are 12 and 18

Doesn't count.  You have to show your work.

[High Plains Drifter 11024]

 

#2 has multiple answers: one possible is 13 and 28. By "the others" I assume they mean that 28 can be any number up to 40 (or 41 if they consider 0) to be a number.

3 minutes ago, Jerry Callo said:

Doesn't count.  You have to show your work.

 

Edited January 20, 2023 by High Plains Drifter

[Celery Man 20931]

Man, been a second since I did this 

[gernblansten 3196]

[Pato del Muerto 52485]

these are algebra problems. Why in 3rd grade?

1) is 2 variable, 2 equation. 
 

x+y=30 and 3x+2y+72 are the equations. Solve one for one variable- I chose the first solved for y: y=30-x.

then substitute 30-x for y in the second equation, and solve the equation. You get x=12. Then use that to get 12+y=30 and y=18. 
 

one answer, yes?

Edited January 20, 2023 by Pato del Muerto

[Pato del Muerto 52485]

16 minutes ago, Celery Man said:

Man, been a second since I did this 

27 isnt more than twice 14. 

Edited January 20, 2023 by Pato del Muerto

[Guest]

Obligatory:

 

What does it say about my liberal arts degree that instead of doing the best way to calculated it like Celery Man that I just start doing trial and error?

[Pato del Muerto 52485]

For the second one, would it work if you change the parameters to x+y=40 and 2x=y, solve that and then add 1 to y?

eta:  sort of.  Veers away from integers but rounding I got to 13 and 27, add one to 27 and you get 13 and 28 which fits the criteria right?

edit2:  didn’t read the problem correctly. Says one number is ONE more than twice the other, not just more than twice the other. 
 

change the second equation to 2x+1=y.

result is 13 1/3 and 27 2/3. 

Edited January 20, 2023 by Pato del Muerto

[PantsTent 2002]

27 isnt more than twice 14. 

Agree. I get 27 2/3 and 13 1/3.

[ohchaucer 1443]

For the first, it's 12 and 18.  That one's easy and she may have graded that one correctly.

For the second one, though, it doesn't work with whole numbers as written, e.g.:

x+y=41

To solve for x:    y=2x+1

X+(2x+1) = 41

3X + 1 = 41

3x = 41 -1

3x = 40

x = 13 1/3  and y=27 2/3

So, 14 and 27 is close, but doesn't meet both equations.

And here's the REAL kicker, the teacher said x=20 and y=21.

 

Am I crazy?!

[Pato del Muerto 52485]

5 minutes ago, ohchaucer said:

And here's the REAL kicker, the teacher said x=20 and y=21.

That’s bullshit. 
 

Ask for the proof!

Edited January 20, 2023 by Pato del Muerto

[PantsTent 2002]

For the first, it's 12 and 18.  That one's easy and she may have graded that one correctly.
For the second one, though, it doesn't work with whole numbers as written, e.g.:
x+y=41
To solve for x:    y=2x+1
X+(2x+1) = 41
3X + 1 = 41
3x = 41 -1
3x = 40
x = 13 1/3  and y=27 2/3
So, 14 and 27 is close, but doesn't meet both equations.
And here's the REAL kicker, the teacher said x=20 and y=21.
 
Am I crazy?!

You’re right and teacher is wrong. It happens a lot in my experience.

[Davis Lane 5578]

To all y'all that got the right answers

[Gene Parmesan 4002]

The teacher probably miswrote the second one.  The first is easy enough numbers that it could be solved by guess and checking with arithmetic rather than an equation.  The goal is probably to get the student to do a bunch of simple addition and multiplication.  Unless your daughter is in a private school they aren't teaching this level of algebra in 3rd grade.

[ztejas 43411]

10 minutes ago, ohchaucer said:

For the first, it's 12 and 18.  That one's easy and she may have graded that one correctly.

For the second one, though, it doesn't work with whole numbers as written, e.g.:

x+y=41

To solve for x:    y=2x+1

X+(2x+1) = 41

3X + 1 = 41

3x = 41 -1

3x = 40

x = 13 1/3  and y=27 2/3

So, 14 and 27 is close, but doesn't meet both equations.

And here's the REAL kicker, the teacher said x=20 and y=21.

 

Am I crazy?!

No but your kid's teacher may be retarded. 

And like someone else pointed out - system of linear equations is a bit steep for 3rd graders even if they're gifted. Unless she just wants them to randomly guess and check numbers. 

[Celery Man 20931]

Not surprised I fucked up one of them

[ztejas 43411]

1 minute ago, Celery Man said:

Not surprised I fucked up one of them

If it makes you feel any better you did the math right you just set the equation up incorrectly. 

[Celery Man 20931]

12 minutes ago, ztejas said:

If it makes you feel any better you did the math right you just set the equation up incorrectly. 

ahhhhh i see where i fucked up

Edited January 20, 2023 by Celery Man

[futureman 22440]

1 hour ago, High Plains Drifter said:

#2 has multiple answers: one possible is 13 and 28.

28 is one more than 26?

[gernblansten 3196]

[Celery Man 20931]

For 20 and 21 to have made sense at any point, I think that the teacher made a mistake in writing the questions rather than doing the math.

[Pato del Muerto 52485]

6 minutes ago, Celery Man said:

For 20 and 21 to have made sense at any point, I think that the teacher made a mistake in writing the questions rather than doing the math.

It’s also more reflective of a third grade level problem that way. 

[Celery Man 20931]

I was generally in the smart kid math classes up until I did AP stat over calculus or whatever, and this would definitely have been either late 6th grade or early 7th. 6th was getting into actual algebra and maybe up to this level, 7th was this, quadratic equation, etc. 

I'm also now unlocking memories of my actuary dad giving me an HP-41C to use in 6th grade because he thought that I would find reverse polish notation neat. And memories of getting a TI-83 and using that little cable to download a Galaga from Ben Dolan.

[ohchaucer 1443]

10 minutes ago, Pato del Muerto said:

It’s also more reflective of a third grade level problem that way. 

Yes, exactly.  And "bonus challenge" questions aren't related to core curriculum, they're intentionally big stretches to get the kids thinking about math concepts and logic.  Nevertheless, you would hope the teacher would write answerable questions, knowing parents are going to be helping out.  

[Native Horn 3498]

nerd alert

[ztejas 43411]

12 minutes ago, Celery Man said:

I was generally in the smart kid math classes up until I did AP stat over calculus or whatever

I did that because our calc teacher was a fucking buffoon and our AP stats teacher was one of the best teachers at the school (who I had already had for ALG2). I was in calc for 2-3 weeks and had to get permission from the stats teacher to transfer because it was past the accepted window or whatever. 

Great decision as I aced stats, got college credit, then took a couple easy business calc classes in college. 

Edited January 20, 2023 by ztejas

[High Plains Drifter 11024]

1 hour ago, Pato del Muerto said:

For the second one, would it work if you change the parameters to x+y=40 and 2x=y, solve that and then add 1 to y?

eta:  sort of.  Veers away from integers but rounding I got to 13 and 27, add one to 27 and you get 13 and 28 which fits the criteria right?

edit2:  didn’t read the problem correctly. Says one number is ONE more than twice the other, not just more than twice the other. 
 

change the second equation to 2x+1=y.

result is 13 1/3 and 27 2/3. 

 

Yeah, i misread also. Reading correctly, the second one is also 2 variables, 2 equations. I solved it as an inequality. I also didn't consider that fractions would be considered numbers also.

 

 

[High Plains Drifter 11024]

 

Also, these problems are above 3rd grade, but they are also "challenge" problems. To give the nerds something to do while the bangers and the jocks are puzzling out long division.

[High Plains Drifter 11024]

 

One more also, third grade teachers don't have math degrees, they have general elementary education degrees. Cut her some slack.

[ztejas 43411]

I guess #2 was just a typo and they meant "one number is one more than the other".

[Crapinon 2252]

2 hours ago, Jerry Callo said:

Doesn't count.  You have to show your work.

 

[Celery Man 20931]

1 hour ago, ztejas said:

I did that because our calc teacher was a fucking buffoon and our AP stats teacher was one of the best teachers at the school (who I had already had for ALG2). I was in calc for 2-3 weeks and had to get permission from the stats teacher to transfer because it was past the accepted window or whatever. 

Great decision as I aced stats, got college credit, then took a couple easy business calc classes in college. 

i'm glad I eventually took calculus at Texas (although... just k and l and they ended up being electives) but I don't regret AP Stat at all. I don't know what's required in math for high school students these days but a solid foundation in statistical analysis is as important as anything else in the modern educated workforce imo

[Pig Bellmont 8712]

2 hours ago, Celery Man said:

ahhhhh i see where i fucked up

This isn’t some mundane detail, Michael!

[52-80 19142]

What chatgpt for if not for this

[52-80 19142]

Wolfram alpha is dumb as shit

[elfenix 34221]

for the second one i just divided 40 by 3 in my head and got the right (not by teacher's math, but actual right) answer

[ztejas 43411]

51 minutes ago, elfenix said:

for the second one i just divided 40 by 3 in my head and got the right (not by teacher's math, but actual right) answer

[Doze 1322]

[NWBuck 8552]

[RPM 26315]

220, 221, whatever it takes

[Incredulity 11646]

18 hours ago, ztejas said:

calc teacher was a fucking buffoon

Csb alert.

my high school calculus teacher was bi-polar or some sort of mental.  He fucked a friend of mine out of co-valedictorian with a second semester B+ even though he never missed a class or test question.  Administration wouldn’t do anything about it.  In today’s day and age lawsuits probably fly over shit like that.

[Incredulity 11646]

18 hours ago, High Plains Drifter said:

the bangers and the jocks are puzzling out long division.

What about the sportos, the motorheads, geeks, sluts, bloods, wastoids, dweebies and dickheads?

Edited January 21, 2023 by Incredulity

[RPM 26315]

2 hours ago, Incredulity said:

my high school calculus teacher was bi-polar or some sort of mental.  He fucked a friend of mine out of co-valedictorian with a second semester B+ even though he never missed a class or test question.

Edited January 21, 2023 by RPM

[Incredulity 11646]

What does Tim Whatley DDS have to do with this?

[Brew 3049]

20,21 and 41 is one more than 2x21. It makes zero sense to write it out that way but technically you could argue the facts are correct because it just says one number not one of the variable. It is just not solvable in the way it is written as there would be too many variables. Teacher is dumb.

[Nivek 16916]

3 hours ago, Incredulity said:

Csb alert.

my high school calculus teacher was bi-polar or some sort of mental.  He fucked a friend of mine out of co-valedictorian with a second semester B+ even though he never missed a class or test question.  Administration wouldn’t do anything about it.  In today’s day and age lawsuits probably fly over shit like that.

Good life lesson.  Some people fuck you over for no reason and some people have no business in education.  

[SilasCoade 2622]

23 hours ago, ohchaucer said:

Yes, exactly.  And "bonus challenge" questions aren't related to core curriculum, they're intentionally big stretches to get the kids thinking about math concepts and logic.  Nevertheless, you would hope the teacher would write answerable questions, knowing parents are going to be helping out.  

That's not true. Some parents are going to be too busy or too dumb to fuck with this shit and some parents are going to tell their kids to figure it out. I've got a senior in high school right now and last year was the first time I helped her figure out any math homework. Determining whether that's b/c I'm busy, dumb, or an asshole is an exercise left to the reader.

[NAVY 6740]

Math fight!!!!!!!!!!

Yeah, #2 is likely typo-ed