can anyone explain....

[katarina]

can anyone explain this riddle to me. A man stops at a market stall and notices a camera amd case set priced at £310.00. The seller tells him that the camera costs £300.00 more than the case. But that the case costs the price of the set minus the cost of the camera. If the man decides to buy the case only and gives the seller a £100 note, how much change will he get back?
I immediately thought £90. But apparently that is not the right answer. I now know what the answer is, but cant for the life of me understand why it is what it is. Help!

[daviddd]

The answer could be 'none' - no change from £100.....reason being, the seller was selling the 2 items together so it's still £310 for both or either one of the 2 items?

[stewart4364]

He would get £95 back. If the camera and case cost £310 but the camera costs £300 more than the case the camera must cost £305 and the case £5 a difference of £300. It is no riddle just a case of simple arithmetic.

[katarina]

that is the answer. but it still seems to me that if the case cost £10 and the camera £300 There is still a difference of £300. I mean £300 plus £10 equals £310? Maybe my brain just doesn't work that way.

[gillian17]

Use algebra
x is the camera y is the case
x + y = 310
x = y + 300
Add the two equations together
2x +y = y + 610
2x = 610
x = 305
Therefore y=5

[brokencross]

Use algebra
x is the camera y is the case
x + y = 310
x = y + 300
Add the two equations together
2x +y = y + 610
2x = 610
x = 305
Therefore y=5

I knew simultaneous equations would have a use in later life!

[honey]

have you been playing Professor Laytons Curious Village too??

[katarina]

Use algebra
x is the camera y is the case
x + y = 310
x = y + 300
Add the two equations together
2x +y = y + 610
2x = 610
x = 305
Therefore y=5

I'm with you until add the two equations together. I would say
x + y = 310
x = y + 300
therefore y =10. If I was at school would I be marked wrong?
I would not see the neccessity to add the equations together. Is this really mathematically correct? Or is it just one of these conundrums? I mean seriously, if you were the man buying the case and it cost you £10 would you or would you not think you'd be being shortchanged. i mean in real life?

[katarina]

have you been playing Professor Laytons Curious Village too??

Did you get that one?

[honey]

Did you get that one?

nope, think hubby got it, but i couldnt for the life of me work it out....

[gillian17]

Katarina try adding the equations together again I cannot understand how you can get y=10. Or try working it out as y=10 It does not work out Trust me sweetheart Mathematics is my forte.

[katarina]

Katarina try adding the equations together again I cannot understand how you can get y=10. Or try working it out as y=10 It does not work out Trust me sweetheart Mathematics is my forte.

I dooo trust you. I just find it difficult to see. Yes I see how you have worked it out, Why do you have to add the equations together in the first place?
All I see is a case that costs £10 and a camera that costs £300. Add them together and the set costs £310. Simple.

If the case cost £5 and the camera cost £305. and set would still cost £310, but the cost of camera would be £305 more than the cost of the case. Okay. so at 305 it is 300 more than PRICE of the case, then the case cost is added on top of that for the set, but I don't think the question makes that clear. Obviously it does to you and a few others - but please tell me there are others like me who adhere to the simple things in life!

[ravenblueice]

OK how about why it isn't £10 for case and £300 for Camera... if the camera costs £10 more than the case and the case is £10 the camera would have to be £310 (£10 plus £300)and the total would be £320...

I.e. if the camera costs £300 plus the value of the case, the total for the set must be £300 plus two cases.

So to work out the values of each look at the total for the set(£310) take away the Difference between the two (£300) and you have the value of 2 cases i.e. using the algebra(sort of)

£310 (total) = {Camera} + Case = {£300 +Case} +Case
so
£310 = £300 + 2 cases
===>(take £300 from both sides)
£10 = 2 cases
===>(divide both sides by 2)
£5 = 1 Case

So taking original sum
£310 = {Camera} + Case = {£300 +Case} +Case
£310 = {£300 + £5} + £5

Hope this clears it up for you, and that I've not gone overboard <g>

can anyone explain this riddle to me. A man stops at a market stall and notices a camera amd case set priced at £310.00. The seller tells him that the camera costs £300.00 more than the case. But that the case costs the price of the set minus the cost of the camera. If the man decides to buy the case only and gives the seller a £100 note, how much change will he get back?
I immediately thought £90. But apparently that is not the right answer. I now know what the answer is, but cant for the life of me understand why it is what it is. Help!

[katarina]

ooooo-k. I guess I've misread the question. The price of the set is when the camera is 300 more than the case, then the case is added on after that. I can see it using that concept. the way i was seeing the question is that the set costs 310, i still have difficulty grasping why you would have to add the cost of the case on after that, as the case is included in the set. I got pretty good marks at school too. maybe different people have minds that work in different ways. one side of the brain being lodical and one being artistic and everyone favouring one or the other. my artistic side is stronger. Could that explain it?