Are you smarter than a 12-year-old? #1 \ stacker news ~science

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250 sats \ 9 comments \ @cryotosensei 6 Oct science

zaps forwarded to @south_korea_ln (21%)

Well, just thought I would start an occasional series on notoriously challenging Maths problems that appeared in Singapore’s Primary School Leaving Examination. Some of these problems plagued me during my childhood. High time for me to learn how to solve them so that I can train my son to beat the system.

This question appeared in the 2012 paper.

A bakery and a library are 120m apart. They are located between Hong’s house and Jeya’s house, as shown below. The bakery is exactly halfway between the 2 houses.

One day, Hong and Jeya started cycling from their houses at the same time and they arrived at the library together. Jeya cycled at 70m/minute while Hong cycled 15m/minute faster than Jeya.

a) How much further did Hong cycle than Jeya? b) How far is Jeya’s house from the library?

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114 sats \ 3 replies \ @premitive1 7 Oct

a) 240m b) 1120m

I didn't check my work

37 sats \ 2 replies \ @cryotosensei OP 7 Oct

Well done! You are right.

But we don’t teach elementary school children how to form equations. It’s cognitively too abstract for them.

Here’s how the kiddos are supposed to solve this.

Of course, if a precocious kid were to solve this problem using your method, he would be awarded full marks.

37 sats \ 0 replies \ @south_korea_ln fwd 8 Oct

I wonder what was the success rate...

Just watched the video... this is like solving equations without calling them equations... not sure if this way is easier or more intuitive :)

0 sats \ 0 replies \ @premitive1 8 Oct

for the record, my work started with the two bottom lines, and then the two lines above. I don't explain my work, but a math teacher like you will recognize what's going on.

this is simply what came to me. maybe we should teach elementary children how to form equations.

48 sats \ 1 reply \ @Murch 9 Oct

The bakery is right between Hong’s house and Jeya’s house.
The library is 120 m closer to Jeya from the bakery.
Hong had to cycle to the bakery and then 120 m more.
Jeya had to cycle 120 m less than the way to the bakery.
Hong cycled 2×120 m = 240 m more than Jeya.
They both arrive at the same time, so Hong cycling faster enabled her to cycle 240 m more. Per , we learn that Hong and Jeya cycled for 16 minutes.
In 16 minutes, Jeya cycled to the library.

0 sats \ 0 replies \ @cryotosensei OP 3 Nov

I bookmarked your solution. It’s so elegant - and you used logic to arrive at the answer.

24 sats \ 1 reply \ @User21000000 6 Oct

No I’m not

0 sats \ 0 replies \ @cryotosensei OP 7 Oct

Me neither, actually

0 sats \ 0 replies \ @rebel_nomad 6 Oct

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