up the garden path...

[Brigadier]

Obtusely, reminds me of the smug engineer who starts patronising the "thick" bricklayer who is building a garden wall for him.

"In my line of work," the engineer says, "I work to tolerances of a thousandth of a millimetre!" He is clearly very pleased with himself.

The brickie looks up from his wall, and casually replies,

"Really? In my job, I work to cock on."

 

[matt1e]

I just seen this

Untitled

• r.bartlett
• 19 Sep 2012
• 1

I think some one needs to teach the teacher the difference between 3 decimal places and 3 significant numbers or at least you would think they would notice if it is a mistake on the paper

the correct answer for that question to 3 decimal places is 4.950 to 5.049

 

[r.bartlett]

Well it's a maths exam question, some would say testing mathematical principles matter when taking a maths exam. Does that make me an old git?

But it's also a GCSE so let's not make it too mathematical, the little darlings might not like that, too hard and they all have to get A*s now......

Interesting none of us got the 'approved' answer, even the teacher seemed to get it 'wrong', how old is teacher out of interest?

Don't know but my daughter is 10

 

[chapeau]

well i never! Its in the GCSE syllabus by the looks of it, thought thats where it came from. So she gets taught it one way at ten, then at GCSE another way? I still reckon teacher is correct

 

[conny]

4,500mm rounded up
or
5,499mm rounded down.

 

[matt1e]

well i never! Its in the GCSE syllabus by the looks of it, thought thats where it came from. So she gets taught it one way at ten, then at GCSE another way? I still reckon teacher is correct

Teacher is correct but her answer (5.04) is to 2 decimal places not three (it's 3 sig figs)

 

[chapeau]

Isn't that a different question?

 

[matt1e]

I'm talking about the Ops question Chapeau

Untitled

• r.bartlett
• 19 Sep 2012
• 1

Matt

 

[securespark]

Me and Mrs Secure both sided with Nige.

Obviously we are wrong.

So is the final opinion 4950 - 5040mm?

 

[matt1e]

4950 to 5049 if you ask me as the question concerns Lengths not bounds (that answer would be 4950 to 5050)

 

[chapeau]

The question is almost identical to the one in the link I posted earlier

http://www.bbc.co.uk/schools/gcsebitesize/maths/number/roundestimaterev5.shtml

That's a GCSE resource, from the BBC, with a very very strange explanation of the answer, but the answer it wants to see is clear.

I think if you want to get full marks in a GCSE exam the answer is 4950-5050 (in mm) even though that would appear strange to some of us, including the teacher apparently.

 

[libby lou lou]

I thought 4950-5050 mm is the only answer?.

 

[matt1e]

The question is almost identical to the one in the link I posted earlier

http://www.bbc.co.uk/schools/gcsebitesize/maths/number/roundestimaterev5.shtml

That's a GCSE resource, from the BBC, with a very very strange explanation of the answer, but the answer it wants to see is clear.

I think if you want to get full marks in a GCSE exam the answer is 4950-5050 (in mm) even though that would appear strange to some of us, including the teacher apparently.

Ah I've just read a better explanation, it's to do with Rational numbers
it's because the of the fact that the longest length (taking the ops question for example) could in fact be 5049.9999999999999999999mm which would normally round down but using rational numbers you would show the above as 5050mm


Now about the difference between decimal places and significant figures

 

[securespark]

From that BBC link:

Upper and Lower Bounds

If we are told that a piece of wood is 12cm long to the nearest cm, then what is the range of possible lengths it could be?

It must be at least 11.5cm long to round up to 12cm. But it must be less than 12.5cm, to round down to 12cm. If it was 12.5cm or more we would round up to 13cm.

Since 12.5cm is the upper limit we call this the 'upper bound'.

So we say that 11.5cm is the lower bound and 12.5cm is the upper bound for the length of the piece of wood.

But it says above

But it must be less than 12.5cm, to round down to 12cm. If it was 12.5cm or more we would round up to 13cm.

So surely if they have decided the upper bound is 12.5cm, then the piece of wood must be 13cm to the nearest cm?

Or am I missing something here?

 

[libby lou lou]

Your right.