How quickly can you solve this math problem?

[LuckyCharms]

I just found this on another website. The poster on that site claims that this problem was on his brother's math test. Poster claims his brother is in the 5th grade. I don't know if this person's brother was actually in the 5th grade or not, but I'm assuming the statement is true. I solved this in my head and it took maybe 30 to 45 seconds for me to solve.

I don't know about you, but this type of problem would have been way above my 5th grade learning experience, because it involves algebra, which I don't believe I learned until the 9th grade. Have times changed that much? Are children better educated in math now?

[SarasotaDem]

1. 48 nt

[LuckyCharms]

2. Yes.

Could you have done that in the 5th grade? I would not have been able to.

[SarasotaDem]

5. Probably not ..

But I did like math

[LuckyCharms]

8. Me too. I remember I won a few math "awards" where the teacher

had extra copies of the class photo where each class member had a photo of their face in a separate little square.

If you got an award, the teacher would cut out the picture of your face and make a medal out of it by gluing the picture to some construction paper with a ribbon attached to it, then hang the home made medal up on the classroom wall.

But the problems were addition, subtraction, long division, etc. Nothing like this problem.

[cyclonefence]

3. They're certainly learning stuff we never dreamed of

My son's sixth grade class learned to calculate octane fergodssake.

[Sanity Claws]

4. Not in 5th grade.

We didn't start algebra until 8th grade back in ancient times.

[FakeNoose]

6. I got the answer in about 30 seconds, and I didn't use algebra

It's knowing how to use fractions, really.

The remainder of the book is five-eighths of the book, and 30 pages represents three-eighths.
By dividing five-eighths into 30, you get the answer of 48 total pages.

If they are teaching fractions and word problems correctly, this seems to be fifth-grade level.

[wnylib]

26. That's the method that I used, too.

Math was not my favorite or best subject, although I managed to get Bs in it and occasionally even an A.

I've had intro and intermediate algebra, plane and solid geometry, and trig. But the fractions method, not algebra, leaped out at me from the problem when I read it.

[William Seger]

31. Me too (nt)

[Effete Snob]

7. Pretty quickly

The thing with this is that the "math" is easily 5th grade level.

This sort of problem is geared more toward developing a strategy to solve it, and there are some kids that aren't all that good at computation, but are good at visualizing how to solve this.

Adults too.

Some people will just be intimidated by the fact that it is a math problem of some kind.

Other people will quickly realize that 30 pages was 5/8 of the book (since there were 3/8 of the book remaining after Monday, i.e. 1/8 and 2/8).

From there, some folks will set up (5/8)x=30 and do it symbolically, which is my tendency, while other people will just do the proportion in their head.

With calculators, I doubt as much time is spent teaching kids to compute, as opposed to finding strategies for tackling problems.

[LuckyCharms]

12. My thought process was...

OK...1/4+1/8 = 2/8+1/8 = 3/8. That means that 30 pages is 5/8's of the whole book...what number is roundly divisible by 8? Let's see...48, does that work? Then I thought 1/8 = 12.5% so 5/8's =62.5 percent. Is 30, 62.5% of 48? Yep, that looks about right, 48 pages.

if I worked it out with a pen and paper, I might have done it a bit differently.

[Effete Snob]

15. When I do that...

...I get lost.

I usually end up stuck on one computation and then forget where I was going with it, and start over.

Part of the problem is that once I see where to go in order to solve the problem, I lose interest in the answer. But the other part is that I suck at computation. I can puzzle over a golf score card for a while and not know the total score, because I will think of several quick ways to do it, but not do any of them.

I have to set it up on paper.

[William Seger]

32. I just thought, 30 pages is 5/8ths, so 1/8th is 6 pages, so 8/8ths is 48 (nt)

[old as dirt]

17. A calculator is like a security blanket.

If a calculator is allowed but not required on a 50 minute exam, I try to write the exam so that it can be done calculator-free in 40 minutes, and then allow another 10 minutes extra to give the students with calculators time to play with them.

[Phentex]

22. When did you look at me?

Some people will just be intimidated by the fact that it is a math problem of some kind.

[OAITW r.2.0]

9. 48. Did not look at other responses yet.

[DetlefK]

10. length equals 30 + 1/8 * length + 1/4 * length

30 = 5/8 * length
length = 48

[padah513]

11. Googled it

[Effete Snob]

16. I asked ChatGPT

It told me all about the book and said it had hundreds of pages.

[old as dirt]

13. Sure, it's an algebra problem at heart, but...

...but one doesn't need to write down any equations to note that 5/8 of the book is 30 pages.

So 1/8 of the book is 6 pages.

That makes the whole book 48 pages long.

[keithbvadu2]

14. The math itself is fairly easy. Figuring out the math procedure is the real problem.

The math itself is fairly easy.

Figuring out the math procedure is the real problem.

[Pobeka]

18. This is a very old printed problem -- how do I know?

Look, and you can see ghosting of the print from other pages on the sheet presented here.

Which means, it has sat closed for long enough time that the print dyes could transfer from one sheet to another.

The darkness of the paper is another clue.

I'm going to guess this is about a 30 year old piece of paper, paper won't generally darken very fast if it's closed up and protected from UV light.

[Effete Snob]

24. So...

We don't know how many pages the book has, but we know how old it is.

That would have been a lot better for the call of the question, "How old is the book?"

Since he read it just that week, then the book is at least as old as the question.

[Donkees]

19. Who's Klein?

[Chainfire]

20. I got by in math in school, I had I the same horrible math teacher throughout high school.

(A PE major forced to teach math; a problem in rural schools) I was way behind the eight ball on math and science when I started college. We graduated thinking that physics was something you did in the gym. I started learning practical math problem solving as an apprentice plumber. You may be surprised about how much ciphering goes into designing and installing plumbing systems.

[LuckyCharms]

21. People who are not in the trades sometimes do not appreciate

the amount of logic and complicated math that is involved in every trade.

And most of that math is done on the fly, in your head, without pencil and paper.

Work in the trades also requires the ability to visualize outcomes...an ability that many people do not have.

[IcyPeas]

23. No clue. I once found "x" though

[Effete Snob]

25. I did too, but I lost it again

[GoodRaisin]

27. Well, you know your alphabet.

[Effete Snob]

29. That was my favorite cereal

One time, I was eating breakfast and my brother told a joke.

I laughed so hard the cereal came out my nose, landed on the table, and spelled out “JESUS”. I was going to wipe it up, but my mom stopped me and called Father Murphy. He said to leave it there until he could come by later and take a look at it to decide if it was a miracle.

He came by a couple hours later, looked at it and talked to all of us, and asked me if I had any visions the previous night. Well, yeah, I had, but I didn’t know if he wanted to know what of or how I cleaned up my pajamas after I woke up, so I said no.

He decided it wasn’t a miracle, but by the time it was okay to remove the cereal from the table, it has been there so long that it had sort of dried out and something in the sugar coating had reacted to the finish of the table and - boom - there it remained permanently etched into the surface. We tried to wipe ir off but he said, “Wait, no, look, it’s still there!” and THAT, he decided, was a miracle.

So my dad cut a piece of plexiglass and screwed it over the spot since we couldn’t afford a new table but we couldn’t mess up the miracle that happened in our very own kitchen. Eventually, some of the people at church raised some money to buy us a new table and we donated it to the church, where they cut out that part and put it in a little chapel where you can go pray and light a candle. They say that the words just appeared there and don’t tell the whole thing about it coming out of my nose in the first place.

I spent years trying to make that happen again and I’d even pick out the letters that would spell out words on purpose to do it. Like, I tried to get “GOD” and it only came out “DOG,” so I guess maybe it was something of a miracle if you think about it.

[RockRaven]

28. I'm curious if the student is supposed to set up an algebraic equation and solve it, or just

logic their way through it without formal notation.

For instance, you don't need to write down an equation to say to yourself:
"The whole book is composed of 30 pages and 1/8 of the book and 1/4 of the book... Which is the same as 30 pages and 3/8 of the book... Which means that 30 pages is 5/8 of the book... If 30 pages is 5/8 then 1/8 is six pages, so 8/8 is 48 pages"

Or you can say:
"Let's make x the book length, and then x = 30 + x/8 + x/4, and now I will solve for x... Etc"

Nobody in my family has been a 5th grader recently, so I don't know how math is being taught at that age these days. Anyone know what method the teachers are expecting (if it is indeed a 5th grade problem)?

[Effete Snob]

30. Probably work through it

A lot of fractional problems are posed such that there are multiple pathways to reason through them. I remember when I finally took Algebra - which was the first “real math” - and feeling a little let down that a lot of it was learning a formal approach to stuff we’d already been doing under different guises - like filling in blanks or empty boxes in equations to make them work, like…

5 + _ = 7

Who knows what it’s like now, but that sort of thing seemed ubiquitous long before algebra.

But, in retrospect, it’s easy to say, “oh, that’s an algebra problem.”

[Sogo]

33. Without looking at any other responses...

My answer would be 48..