Maths Problem

[TheChair]

Apologies if this is the wrong section, but I can't seem to find a more appropriate one.
My Granddaughter has been given the following maths question, which seems to have a mistake in the question. Anyone any comments, please?
There are two bags which contain some prizes. Each bag has the same value.
A large prize is worth £850
A medium prize is worth £500
A small prize is worth £320
The value of mini prize is unknown.

Bag A contains 1 Small, 1 Medium and 1 Mini
Bag B contains 1 Large and 2 Minis

What is a Mini prize worth?

[Helewel]

£30

[elliemay1]

I can't see a mistake. Mini=£30

[rockyracoon]

That would make bag A £850 and bag B £910.

Am I being thick?

[Buenchico]

Hmmm:

320 + 500 + x = 850 +2x

820 + x = 850 + 2x

820 = 850 + x

x = -30

Some prize! The winning contestant has to hand over thirty quid!

[rockyracoon]

Sorry, bag A would be £820

[twix123]

Minus £30 (using simple equations)

[emeritus]

Is that right ?

Bag a 320 + 500 + 30 = 850

Bag b 850 + 30 + 30 = 910.

They have to be the same. Unless I’m missing something

[Davemano]

I think the mistake is the mini bags, A should have 2 and B should have 1 - making each bag value £880

[Mamyalynne]

Twix has it.

[New Judge]

Yes, there is something wrong with the question.

Bag A = £320 + £500 + 1 mini.
Bag B = £850 + 2 minis.

So, Bag A = £820 plus 1 mini
Bag B = £850 plus 2 minis.

So, let the value of a mini be x. Then

820 + x = 850 + 2x.

Under the above scenario Bag B must be worth more than bag A. They cannot both be of the same value. The only way to get the equation to balance is to make the value of a mini a negative number. Minus 30, in fact, meaning 820 – 30 = 850 – 60.

Clearly nonsense.

[Mamyalynne]

Not sure why it's a nonsense, minus numbers do feature in Maths Homework.

[New Judge]

"Not sure why it's a nonsense, minus numbers do feature in Maths Homework."

Quite so. But this is supposed to be a practical problem. How many prizes have a negative value?

[Mamyalynne]

I'll leave it, well done Twix.

[elliemay1]

To be fair Mamyalynne, Buenchico had it first!

[Davemano]

If minus £30 is right, the problem should have simply stuck to numbers as it seems nonsense to have prizes with minus values.

[New Judge]

Yes but pupils should not have to identify mistakes in questions that are set for them. Shoddy teaching.

[Mamyalynne]

Missed that sorry, Twix was concise - well done Chris.x

[jim360]

The problem isn't so much when teachers make mistakes -- it's how they react to them when they are pointed out.

Something as elementary as this (apparently) seems a bit of a shocker though. Looks like the minis were assigned the wrong way round.

[Buenchico]

It's perfectly possible that the teacher HASN'T made a mistake.

When I was at school we were often required to copy homework questions down from the blackboard. It was just the same when I was teaching in the 1970s and 80s. I suspect that (apart from the fact that it will now be a whiteboard) things haven't changed very much.

So a simple error by a pupil copying from the whiteboard could be the cause of the problem here.

[Davemano]

Yes jim, exactly the point I was making 23.22