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GCSE revision Maths



Bruntburger

New member
Mar 9, 2009
1,138
Peacehaven
My daughter is preparing for her maths exam tomorrow and has been working through this practice sheet.

Any ideas how to answer this question?

I would of just worked out the mean average but not allowed a calculator in the exam.

Any input from boffins welcome .....
ac649a8a3ce9f48338c943b428842640.jpg
 




chimneys

Well-known member
Jun 11, 2007
3,582
Lizzie (just).

Not difficult to get means is it, even without a calculator.

Is there a catch?
 


carteater

Well-known member
Jan 1, 2014
4,825
West Sussex
I assume they want you to work out an average/mean without a calculator, EDIT the post below makes that very easy.
I always hated non-calculator maths papers.
It's Lizzie anyway.
 


Aristotle

Active member
Mar 18, 2008
604
Edinburgh
Since they are all 26-something times, just add up the number after the decimal point in each case and divide by the number of times to get an average for each girl.
 






HAILSHAM SEAGULL

Well-known member
Nov 9, 2009
10,346
Add Lizzie's 5 times up and divide by 5, this gives her average time.
Add Megans 6 times up and divide by 6 to give her average time.
 


hans kraay fan club

The voice of reason.
Helpful Moderator
Mar 16, 2005
61,094
Chandlers Ford
My daughter is preparing for her maths exam tomorrow and has been working through this practice sheet.

Any ideas how to answer this question?

I would of just worked out the mean average but not allowed a calculator in the exam.

Any input from boffins welcome .....
ac649a8a3ce9f48338c943b428842640.jpg

Because ALL the times are 26.X you can ignore the whole seconds and just work out the average of the .X part.

First swimmer is 20 tenths / 5 = 26.4
Second is 30 tenths / 6 = 26.5

Select the first.
 




Bruntburger

New member
Mar 9, 2009
1,138
Peacehaven
Because ALL the times are 26.X you can ignore the whole seconds and just work out the average of the .X part.

First swimmer is 20 tenths / 5 = 26.4
Second is 30 tenths / 6 = 26.5

Select the first.

That's great. Thank you all for your help.
Maths isn't my strong point!
Come to think of it neither is English.
Cheers
 


dazzer6666

Well-known member
NSC Patreon
Mar 27, 2013
52,011
Burgess Hill
Lizzie has a faster mean of 26.4 (vs 26.5) so I'd select her.
Whilst Megan has the overall single fastest time, this looks inconsistent with the rest of her performances (she is less consistent generally with a greater range of times)
Megan should be told not to use the vending machine after swimming, then she'll get faster and make the team next time
 


Springal

Well-known member
Feb 12, 2005
23,711
GOSBTS
And regardless of the outcome of this exam, your daughter will be in a job where she can use a spreadsheet to work this stuff out rendering this Maths exam completely pointless.
 




Goldstone1976

We Got Calde in!!
Helpful Moderator
NSC Patreon
Apr 30, 2013
13,765
Herts
Since it's a maths test, what you've been told is correct. In the real world, however, I might be inclined to pick the second swimmer, on the basis that her average time is only 0.1s slower than the first's but she has swum the fastest time. On her best day, she's the (slightly) faster swimmer.
 


timbha

Well-known member
Jul 5, 2003
9,834
Sussex
Deduct 26secs from every trial, e.g. 1st one is 26.3 - 26 = 0.3

Add up the total of what's left and divide by number of swims for each swimmer,

Ave for Lizzie is 2.0/5 = 0.4 + 26 = 26.4
Ave for megan is 3.0/6 = 0.5 + 26 = 26.5

So Lizzie has faster average time, but
Megan had the fastest swim

Teacher has to decide if he/she wants the most consistent or fastest swimmer. Is this a trick question?
 






Paul Reids Sock

Well-known member
Nov 3, 2004
4,458
Paul Reids boot
My wife had to resit her maths a few years ago. Big bit of advice I gave her that helped is always ignore the bloody story. It is there to throw you off half the time.

Once you stop thinking of swimming and such crap then it's a simple case of getting the mean.

Also, in this case you could argue that either is correct as the variation in times for the first girl is smaller so you have more of an idea where she will come. The second girl has shown she can swim a lot faster but also a lot slower. So the story here actually doesn't help at all or show what the teacher is after
 


dazzer6666

Well-known member
NSC Patreon
Mar 27, 2013
52,011
Burgess Hill
Since it's a maths test, what you've been told is correct. In the real world, however, I might be inclined to pick the second swimmer, on the basis that her average time is only 0.1s slower than the first's but she has swum the fastest time. On her best day, she's the (slightly) faster swimmer.

Freak performance based on normal average times - need to await results of drug tests
 


whitelion

New member
Dec 16, 2003
12,828
Southwick
And regardless of the outcome of this exam, your daughter will be in a job where she can use a spreadsheet to work this stuff out rendering this Maths exam completely pointless.

It still helps to be able to make calculations without the need of a spreadsheet or calculator - the methodology is the important thing.

What happens in a powercut/no computer/no calculator etc.?
 


Springal

Well-known member
Feb 12, 2005
23,711
GOSBTS
It still helps to be able to make calculations without the need of a spreadsheet or calculator - the methodology is the important thing.

What happens in a powercut/no computer/no calculator etc.?

You go down the pub.
 




timbha

Well-known member
Jul 5, 2003
9,834
Sussex
What's the most appropriate measure ?
Mean, median, standard deviation, average, fastest, slowest - each one could be relevant
 





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