sharpy28
Member
Registered: 1st Nov 08
Location: Ashton-Under-Lyne (Manchester)
User status: Offline
|
Use algebra to solve the following:
Water is being drained out of a tank through 2 pipes at the rate of 330L/Min.
We know that one pipe releases 50L/Min more than the other.
How much do the 2 pipes each drain?
.............
A mate gave me this answer:
A+B = 330
B = A - 50
2A - 50 = 330
2A = 380
A = 190
------------------
B = A - 50
B = 190 - 50
B = 140
Any help will be much appreciated
|
Gaz
Member
Registered: 24th Aug 03
Location: Widnes, Cheshire
User status: Offline
|
looks right in those workings from a logical prospective
|
3CorsaMeal
Member
Registered: 11th Apr 02
User status: Offline
|
I'm useless at these as I just do it in my head with no workings. Then have to make up the workings from the answer.
|
LeeM
Member
Registered: 26th Sep 05
Location: Liverpool
User status: Offline
|
thats right.
|
Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
|
I would have done;
330/2 =165
50/2 =25
165 - 25 = 140
165 + 25 = 190
No algebra over here
|
M2RTY
Member
Registered: 25th May 01
User status: Offline
|
divide total flow by 2
divide difference between them by 2
add 1 to the other, thats pipe A
subtract one from other, thats pipe B
cant get any easier
|
RichR
Premium Member
Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
User status: Offline
|
That's not algebraic though Marv; same results but technically the wrong route to the answer
|
Budgie
Member
Registered: 2nd Dec 09
Location: Basingstoke
User status: Offline
|
quote:
Originally posted by Robin
I would have done;
330/2 =165
50/2 =25
165 - 25 = 140
165 + 25 = 190
No algebra over here
its how i would of done it.
|
RichR
Premium Member
Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
User status: Offline
|
But the question says use algebra so by virtue of the fact that you wouldn't have used algebra to get the answer, you wouldn't get all of the marks on offer
|
csweatherston
Member
Registered: 16th Jan 06
Location: Devon
User status: Offline
|
Would you not normally get full marks for having the correct answer?.
But if you had an incorrect answer get partial marks for the right working?
|
Hammer
Member
Registered: 11th Feb 04
User status: Offline
|
Of course not, you could have came to the correct answer by pure chance.
The majority of the marks will be gained by showing how you strategically set out to get to the correct answer.
|
*CorsaCal*
Member
Registered: 3rd Oct 10
Location: Leicestershire Drives: 20XE Corsa
User status: Offline
|
quote:
Originally posted by Robin
I would have done;
330/2 =165
50/2 =25
165 - 25 = 140
165 + 25 = 190
No algebra over here
Agreed
|
Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
|
This just illustrates that algebra is a waste of time. It took 20 seconds to get to the answer, there is no practical application for algebra.
|
spencer88
Member
Registered: 6th Oct 08
Location: cornwall
User status: Offline
|
quote:
Originally posted by Robin
This just illustrates that algebra is a waste of time. It took 20 seconds to get to the answer, there is no practical application for algebra.
Yep!
It is like during exams and stuff, I have been marked down before for doing workings in my head, getting the right answer but not writing down all the workings. Why? If you get the right answer surely you should get full marks, regardless of the workings.
Why should you get more marks for getting a wrong answer but showing your workings?
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Online
|
Because the working out shows you understand what is going on.
There is more credit at that level for a sound application of the techniques, than the arithmetic required to calculate the actual values.
|
Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
|
I understand that they've asked for it but it seems a bit pointless as you'd never use it in the real world.
Surely an exam or whatever it is should be to evaluate you on a skill worth using?
|
spencer88
Member
Registered: 6th Oct 08
Location: cornwall
User status: Offline
|
quote:
Originally posted by Ian
Because the working out shows you understand what is going on.
There is more credit at that level for a sound application of the techniques, than the arithmetic required to calculate the actual values.
Not true.
I know people who have just memorised equations for exams and have no idea what it means. It just shows you can regurgitate equations and such.
|
Hammer
Member
Registered: 11th Feb 04
User status: Offline
|
quote:
Originally posted by Robin
I understand that they've asked for it but it seems a bit pointless as you'd never use it in the real world.
Surely an exam or whatever it is should be to evaluate you on a skill worth using?
An exam is used to evaluate how well you have picked up a particular course. If that is algebra, what worth is there to them in a bunch of correct answers without the application of algebra to get to them?
|
Hammer
Member
Registered: 11th Feb 04
User status: Offline
|
quote:
Originally posted by spencer88
quote:
Originally posted by Ian
Because the working out shows you understand what is going on.
There is more credit at that level for a sound application of the techniques, than the arithmetic required to calculate the actual values.
Not true.
I know people who have just memorised equations for exams and have no idea what it means. It just shows you can regurgitate equations and such.
|
Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
|
Why is algebra being evaluated though? The only career I can think of which you'd need it for us to be a Maths teacher!
|
Hammer
Member
Registered: 11th Feb 04
User status: Offline
|
I use it all the time but then I'm a bit of a sad act.
|
spencer88
Member
Registered: 6th Oct 08
Location: cornwall
User status: Offline
|
quote:
Originally posted by Hammer
quote:
Originally posted by spencer88
quote:
Originally posted by Ian
Because the working out shows you understand what is going on.
There is more credit at that level for a sound application of the techniques, than the arithmetic required to calculate the actual values.
Not true.
I know people who have just memorised equations for exams and have no idea what it means. It just shows you can regurgitate equations and such.
What?
I know a girl who memorised these equations for a property exam, went in and got good grades based on the equations, yet she couldn't even explain a yield! All she knew was what she memorised and in what order the figures would go to make the equation.
So she got the right answer but didn't know what the answer meant.
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Online
|
quote:
Originally posted by Robin
Why is algebra being evaluated though? The only career I can think of which you'd need it for us to be a Maths teacher!
Not at all, I use maths quite a bit in a lot of programming stuff, used algebra specifically to work out prices for stuff that was being sold with a discount where the discount figure was unknown but the source and target prices were fixed. Use it for measuring stuff, working out wastage on lengths of metal for fabrication, use trig to check things are square etc.
I can see its too cool for school to say a lot of the skills you'll never need but I use maths a fair bit in my adult life.
Plus I maintain that even if the equation is memorised, that it still worth credit. That is essentially what the exam is testing - whether or not you can take a set of values and interpolate them in to an equation to come up with a suitable method to solve the scenario.
You'd still need to understand the scenario sufficiently well to apply the correct equation and you'd still need to also actually have a go with the real values. You get credit for doing it all.
This notion of getting the marks even if its wrong is a bit of a myth. You get credit for the things which demonstrate your understanding and in that regard, repeatable application of method is far more important than the actual answer on that paper on that day.
[Edited on 28-11-2012 by Ian]
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Online
|
quote:
Originally posted by spencer88
So she got the right answer but didn't know what the answer meant.
Which you would hope is tested elsewhere on the paper. I agree the maths is only one part of the wider picture and a good paper would catch that. Although that does indicate to me that she was historically strong mathematically but the lessons on that particular subject didn't do the job.
Was the question 'what is a yield' not on there?
[Edited on 28-11-2012 by Ian]
|
spencer88
Member
Registered: 6th Oct 08
Location: cornwall
User status: Offline
|
quote:
Originally posted by Ian
quote:
Originally posted by spencer88
So she got the right answer but didn't know what the answer meant.
Which you would hope is tested elsewhere on the paper. I agree the maths is only one part of the wider picture and a good paper would catch that. Although that does indicate to me that she was historically strong mathematically but the lessons on that particular subject didn't do the job.
Was the question 'what is a yield' not on there?
[Edited on 28-11-2012 by Ian]
No, it was kind of taken that people understood what a yield was. Questions after the equations would then be, work out the value of... using the yield from Q1 or similar.
|
