Dumb GCSE maths question
Discussion
DeuxCentCinq said:
marshalla said:
Why do I get the feeling there's an underlying "square centimetres" vs. "centimetres squared" problem in the question ?
What's the difference?This is incorrect.
cm² is a unit of measure and not a mathematical formula to be expanded.
DeuxCentCinq said:
marshalla said:
Why do I get the feeling there's an underlying "square centimetres" vs. "centimetres squared" problem in the question ?
What's the difference?RichB said:
DeuxCentCinq said:
marshalla said:
Why do I get the feeling there's an underlying "square centimetres" vs. "centimetres squared" problem in the question ?
What's the difference?Happily, I've not yet come across anyone who would think the latter, so it didn't cross my mind that anyone would be so foolish.
DeuxCentCinq said:
What's the difference?
Confusion can arise because people sometimes use 11 square centimetres to mean an area of 11cm x 11cm, which is 121cm². Other people seem to think that the reverse is the case, with 11cm squared meaning an 11cm x 11cm area.Really this is a problem that should only ever occur when speaking verbally - we have conventions such as the SI system of units to avoid ambiguity like this when writing things down. If an area is presented as 11cm², then it should always mean an area equivalent to 3.3cm x 3.3cm.
tank slapper said:
Confusion can arise because people sometimes use 11 square centimetres to mean an area of 11cm x 11cm, which is 121cm². Other people seem to think that the reverse is the case, with 11cm squared meaning an 11cm x 11cm area.
Really this is a problem that should only ever occur when speaking verbally - we have conventions such as the SI system of units to avoid ambiguity like this when writing things down. If an area is presented as 11cm², then it should always mean an area equivalent to 3.3cm x 3.3cm.
Speaking verbally, as opposed to?Really this is a problem that should only ever occur when speaking verbally - we have conventions such as the SI system of units to avoid ambiguity like this when writing things down. If an area is presented as 11cm², then it should always mean an area equivalent to 3.3cm x 3.3cm.
marshalla said:
Why do I get the feeling there's an underlying "square centimetres" vs. "centimetres squared" problem in the question ?
No, in GCSE ..... cm² is always interpreted as a unit of area, rather than a formula (although some students do get confused and square the 11 as you suggest, most typically in subsequent steps - the most recent example being in 3D Pythagoras' Theorem when using 2D pythag twice over, but I digress).It's more that the question's author had no concept of how far model paint goes (especially when dropped) and had a block 4cm by 3cm by 2cm that needed painting but didn't want the answer to be one tin.
Then we wonder why students think maths sucks and has no use in real life.
Edited by sad61t on Monday 27th April 17:24
DeuxCentCinq said:
Maybe he works for Humbrol, and is trying to increase sales?
Four tins (I double-checked the mark scheme) to cover a typical 1/72 panzer turret, yes Humbrol would be doing very well indeed. 
I guess my main beef is that it derails the "Does your answer sound sensible?" check.
CoolHands said:
timbo999 said:
If the block is 4cm by 3cm by 2cm, its surface area is 2x4x3 + 2x3x2 + 2x4x2 which is 52 cm2... so it needs slightly over 5 tins not 4...
Do I deserve a parrot?
he didn't say the block was a cuboid....Do I deserve a parrot?
timbo999 said:
If the block is 4cm by 3cm by 2cm, its surface area is 2x4x3 + 2x3x2 + 2x4x2 which is 52 cm2... so it needs slightly over 5 tins not 4...
Do I deserve a parrot?
No - I hadn't included the factoid that the (4x2) underside of the block wasn't painted, so only 44cm² needs painting; curiously an exact multiple of 11, thus 4 tins. These questions aren't made up at all, are they?Do I deserve a parrot?
But I (along with Coolhands) do award you the
for "slightly over".Gassing Station | Scale Models | Top of Page | What's New | My Stuff