[pappy1vg]

So I'm listening to Tuesday's show because I'm behind on my shows and I had a question about the quiz. On the math question, I'm with Jamie Oliver. I don't really get how if Tom's father is twice his age (8), he would be born. If Tom's father is twice Tom's age, then his dad would be 16, and Tom wouldn't be born.

I really suck at math. Explanations anyone?

[Console]

That part's not really a math question, it's a logic question, and the mistake you're making is allowing Tom's dad's age to be variable while making Tom's 'current age' static, and then reversing that to determine Tom's new age - both should be variable from the start and you're looking for a time when Tom's age, doubled is equal to his fathers age.

T = Tom's age
D = Tom's Dad's age

Solve 2T = D given that when T = 8, D = 31 and a 1:1 increase.

We know the difference in the ages is 23 (D - T = 31 - 8 = 23) and so we know D = T + 23: -

2T = T + 23 => T + T = T + 23 => Subtract a T on both sides => T = 23

Plugging that back into the original formula: -

D = 2T = 2 * 23 = 46

Tom is 23 and his father is 46.

That part is the math question.

[pjordan2000]

Yeah what he said

[Yudster]

I suck at maths, but I thought this was easy - I figured all you need to know is:-

We know the difference in the ages is 23

However I still have that feeling that even though I ended up with the right answer, if it was an exam I would have lost marks for not working it out properly....

[Console]

Do you lose marks for not showing working? I was never sure whether you had to show your working to get full marks, or if the working-out was a backup in-case you got the answer wrong but could show you understood part of the theory.

[Yudster]

I'm not sure about these days. Back in the dark ages we were always led to believe that if you didn't "show your working" you wouldn't get full marks, but I imagine that is one of many things which has probably changed.

[Latina]

I'm not sure about these days. Back in the dark ages we were always led to believe that if you didn't "show your working" you wouldn't get full marks, but I imagine that is one of many things which has probably changed.

Well it was still that way the last time I did a school maths exam, which was 2000 (Scotland). The good thing about it was you got partial marks if any of your workings were correct even if you'd got lost along the way and given a wrong answer.

Incidentally it was a dreadfully unfair exam that most of the country (including me) would have failed if the SQA hadn't had to lower the pass mark. Actually the Higher exams that year were all a disaster. It was in the news and everything.

[josieeful]

Well, I'm doing my exams this year, and we are told that you should show full working.
So, for example if one question is worth two marks, you would get one mark for the correct answer and one mark for correct, full working out.

[nicowoodcock]

I always thought that if you had the correct answer you got the full marks, regardless if working is shown or not.
But, if you got the answer wrong but had some workings which showed you knew what you were doing but made a stupid mistake, you got partial marks.

[richardtomlinson]

Yes, normally full marks for a correct answer. It's only if you balls it up can your workings then get you marks if you can show that you understand the principles behind the problem.

[Lactating Man Nips]

^^Get some past papers with a marking scheme to see exactly, for each subject, how examiners are guided to award marks for right/wrong answers. You'll find you can still get a good pass without one correct final answer. These can be ordered direct from the examining board (edexcel etc..)

[MK Chris]

I suck at maths, but I thought this was easy - I figured all you need to know is:-

We know the difference in the ages is 23

However I still have that feeling that even though I ended up with the right answer, if it was an exam I would have lost marks for not working it out properly....

Everything she said - I even did it in my head and that's almost unheard of.