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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Original poster

To think that this sum is super simple

536 replies

PeerieBreeks · 11/02/2018 08:26

and can't understand how so many people on Facebook have it so completely wrong (and can justify it to themselves).

Without adding your reasoning, tell me what you think the answer is.

To think that this sum is super simple
OP posts:
Thread gallery
6
CecilyP · 11/02/2018 10:57

^I give six bricks to someone, get a horse.
I get seven bricks back, they get the horse.
I give eight bricks back, I have the horse.
I get nine bricks, they have the horse.

So... That's a £30 pound profit? I started with 6 bricks and now have 9. Why is this so confusing to me!?!? ^

If you only started with 6 bricks where did you get your 8th brick from to complete your third transaction? If you borrowed it, you now have to pay it back reducing your bricks to 8 and your profit £20.

Elendon · 11/02/2018 10:57

Ah yes two different transactions would make it £20 profit.

alpineibex · 11/02/2018 10:57

Ohhhh, I am SO looking forward to my DDs maths homework Blush

alpineibex · 11/02/2018 10:59

Might need to invest me in some of those clicky-cube things they used in primary school.

Elendon · 11/02/2018 10:59

I'm starting with the premise that £60 is the investment, and that's all the money he has.

runningoutofjuice · 11/02/2018 10:59

Alpine, with 10 bricks it is simpler to see your profit because you don't have to borrow any money from a friend or even an unscrupulous lender who might charge outrageous interest rates.

BadLad · 11/02/2018 11:01

I think I know how to make it clear to those not getting.

Imagine the buyers paid the man, who is a horse expert, in advance.

Buyer 1 pays the man 70 to find a horse. The man spends 60 on the horse, and gives it to buyer 1. The man keeps the 10 as profit.

Buyer 2 pays the man 90 to find him a horse. The man now has 100 in his pocket (10 profit from the first sale plus the 90 Buyer 2 has just given him) The man spends 80 of that on the same horse. He gives the horse to Buyer 2, and keeps the 20 profit.

alpineibex · 11/02/2018 11:01

You can do it that way Elendon

But how can you buy the horse back for 80 when you only sold it for 70? By 'borrowing a tenner' which then needs to be subtracted from the profit at the end.

alpineibex · 11/02/2018 11:01

(I think)

CecilyP · 11/02/2018 11:01

You would have had to go to the brick bank for another brick inbetween the sales, so still only 2 bricks profit!

Or as she put it much more succinctly!

alpineibex · 11/02/2018 11:03

So I end up with £90 from my £60, but my friend wants her tenner back.

CuriousaboutSamphire · 11/02/2018 11:05

Alpine let me try

So each of my bricks is a tenner. OK
I give six bricks to someone, get a horse Yes, 1 horse and 4 bricks on the table
I get seven bricks back, they get the horseYes, you have 7 bricks to add to the 4 you already have on the table. You have 11 bricks
I give eight bricks back, I have the horse. Yes, 1 horse and 3 bricks
I get nine bricks, they have the horse Yes, you now have 9 bricks to add to the 3 bricks you already have on the table. You have 12 bricks and no horse.

So you have 2 more bricks that you started with

CuriousaboutSamphire · 11/02/2018 11:06

Sorry I should have confirmed you started with 10 bricks, or, as you say you owe your mate a brick Smile

CuriousaboutSamphire · 11/02/2018 11:07

So I end up with £90 from my £60, but my friend wants her tenner back. Yes 90 - 60 = 30 and then repay your mate her 10 = 20!

upsideup · 11/02/2018 11:09

-60+70-80+90 =+20

Surely its just basic addition and subtraction? Thats the kind of question DS8 gets in his maths homework.

Elendon · 11/02/2018 11:10

It could be an immediate purchase, buying and selling within a period of minutes/seconds, there are no time lapse sequences. If there was a period of years after the first selling then the purchaser makes a profit of £20.

Sagethyme · 11/02/2018 11:11

The problem with this question is you have to assume the man has a minimum of $70 to start with

Elendon · 11/02/2018 11:12

Thanks upside, that makes it very clear!

Obviously I'm hopeless at maths!

Royalfuckup · 11/02/2018 11:13

@Elendon

But even if it is an immediate purchase within a period of minutes/seconds the profit is still $20.

CecilyP · 11/02/2018 11:13

Both the time lapse and his starting amount are irrelevant to his profit.

SoupDragon · 11/02/2018 11:13

The point of these questions is not the maths, it’s understanding how the question is written. Like that “sweets” one from a GCSE paper a couple of years ago.

Sagethyme · 11/02/2018 11:13

Of course the answer could be he has $10 because he realised he couldn't afford to buy it back. Or he took at a payday loan to buy the horse back, realised the interest on the loan was unaffordable sold the horse back and gave all the money and his house back to the loan company Grin

DadDadDad · 11/02/2018 11:15

The problem with this question is you have to assume the man has a minimum of $70 to start with

Not if he does it all through bank payments and he has a fee-free overdraft.

Sagethyme · 11/02/2018 11:19

True dadx3 but then no doubt the inland revenue would want to know, so he'd better keep a % back! Grin

runningoutofjuice · 11/02/2018 11:20

If anyone really struggles with basic maths and is worried they won't be able to support their dc in school, can I recommend these? I work in school and use these all the time. I would even say you don't really need anything else up to the end of KS1. The originals are called Dienes but there are various generic brands around now

To think that this sum is super simple