The school maths question dividing the internet

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#1421321 5-Nov-2015 06:54

eracode:

F*** you, Mitsubishi. I don't like your cars anyway.

That was pretty much my answer also...

Batman

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#1421331 5-Nov-2015 07:32

Easy. But these aren't maths??? More like IQ test?

6FIEND

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#1421410 5-Nov-2015 09:30

MadEngineer: I had this question from when I studied NZCE

That's a much more appropriate question to "test" students with IMHO :-)

(BTW, I have determined the answer, but I haven't found an "elegant" way to solve it)

keewee01

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#1421424 5-Nov-2015 09:51

the dress is definitely white and gold!! (not blue and black)

Oh, wrong question

Fred99

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#1421464 5-Nov-2015 10:28

surfisup1000:
Jaxson: This took me about 10 seconds. How is this difficult?

That may sound knoby but I found that china (?) car parking sequence one WAY more difficult, and that was for 7 year olds...

87, not really a math question though. More a psychological trick.

And experience...
I used to spend a lot of time in business meetings. Learning to quickly read text upside-down is a valuable negotiating skill.

shk292

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#1421600 5-Nov-2015 12:33

6FIEND:
MadEngineer: I had this question from when I studied NZCE

That's a much more appropriate question to "test" students with IMHO :-)

(BTW, I have determined the answer, but I haven't found an "elegant" way to solve it)

Surely that just goes to a quadratic equation which can be solved by the standard formula (answer =12)?

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yitz

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#1421647 5-Nov-2015 13:02

shk292:
6FIEND:
MadEngineer: I had this question from when I studied NZCE

That's a much more appropriate question to "test" students with IMHO :-)

(BTW, I have determined the answer, but I haven't found an "elegant" way to solve it)

Surely that just goes to a quadratic equation which can be solved by the standard formula (answer =12)?

Not everyone can form that equation geometrically, some may struggle with algebraic expressions like the 12-d/2.
For me I see it as the area of the outer 12-by-d rectangle minus the area of the triangle (as area of triangle is half that of rectangle 1/2*base*height)

Jaxson

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#1421650 5-Nov-2015 13:06

shk292:
6FIEND:
MadEngineer: I had this question from when I studied NZCE

That's a much more appropriate question to "test" students with IMHO :-)

(BTW, I have determined the answer, but I haven't found an "elegant" way to solve it)

Surely that just goes to a quadratic equation which can be solved by the standard formula (answer =12)?

I'd approach it as Total area 108 m^2 is created by the area of the square plus the area of the Triangle.

So:

Area of the Square is d times (12-d/2)

plus

Area of the triangle is (d times (12m - (12-d/2))) / 2

=

108

So multiply that lot out, make d the subject and therefore solve for d?

BTR

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#1421657 5-Nov-2015 13:12

I failed School cert maths with 35% and I still got it right.......

shk292

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#1421691 5-Nov-2015 14:06

Jaxson:
shk292:
6FIEND:
MadEngineer: I had this question from when I studied NZCE

That's a much more appropriate question to "test" students with IMHO :-)

(BTW, I have determined the answer, but I haven't found an "elegant" way to solve it)

Surely that just goes to a quadratic equation which can be solved by the standard formula (answer =12)?

I'd approach it as Total area 108 m^2 is created by the area of the square plus the area of the Triangle.

So:

Area of the Square is d times (12-d/2)

plus

Area of the triangle is (d times (12m - (12-d/2))) / 2

=

108 So multiply that lot out, make d the subject and therefore solve for d?

Yep, it comes out as d^2 -48d +432 = 0, and you can apply the standard quadratic formula from there

networkn

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#1421729 5-Nov-2015 15:24

Initially my eyes popped out of my head, but thinking about it for a minute, I worked out how I might get the answer, then I did the calculations and the answer I got was one from the list, then I looked at the angle and used estimation to work out if 6 of those gaps would make a circle, and I knew it was right.

It's an issue someone mentioned to me recently that people these days have lost the ability to ESTIMATE, which affects their ability to check if something is more or less right.

I can't agree more now that I have seen so many instances of it since then!

I probably wouldn't have got it at 15/16 as at school I had a mental block at math, I failed it twice.

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eracode

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#1421735 5-Nov-2015 15:39

shk292:
Jaxson:
shk292:
6FIEND:
MadEngineer: I had this question from when I studied NZCE

That's a much more appropriate question to "test" students with IMHO :-)

(BTW, I have determined the answer, but I haven't found an "elegant" way to solve it)

Surely that just goes to a quadratic equation which can be solved by the standard formula (answer =12)?

I'd approach it as Total area 108 m^2 is created by the area of the square plus the area of the Triangle.

So:

Area of the Square is d times (12-d/2)

plus

Area of the triangle is (d times (12m - (12-d/2))) / 2

=

108 So multiply that lot out, make d the subject and therefore solve for d?

Yep, it comes out as d^2 -48d +432 = 0, and you can apply the standard quadratic formula from there

I also found that the total area ended up as that quadratic equation but it took me a while, using trial and error, to find the correct common factors of -48 and +432.

BTW - the rectangle in the diagram looks like a square but clearly it's not.

Sometimes I just sit and think. Other times I just sit.

MadEngineer

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#1421937 5-Nov-2015 19:42

It's not a square.

108m^2 is the total area of the whole shape.

You're not on Atlantis anymore, Duncan Idaho.

eracode

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#1421941 5-Nov-2015 19:55

MadEngineer: It's not a square.
.

As I had just said.

Sometimes I just sit and think. Other times I just sit.

LennonNZ

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#1421979 5-Nov-2015 21:05

long story.. but..

there are 2 answers...
12 and 36

Lets work it out..

Rectangle and Triangle

d(12−0.5d)+2(0.5(0.5d(0.5)d))=108
−0.25d2+12d−108=0

Use some quadratic formula (a little hard to display here)

d=12 and 36

Of course the image is nothing like that the imaginary shape as the triangle has a negative size or the rectangle does.

(or I got it complete wrong) :-)

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