# GCSE Mathematics

Discussion in 'Mathematics' started by Goretti, Feb 10, 2012.

; -)

2. ### Goretti

Thank you so much! I would really appreciate your help.

If you could check that the answers for Assess 9, question 4, a/b/c/d tally with the question - ie they have 1/8 3/4 9/16 & 41/80, but my son says that can't be right from the table in the student's book - (he gets 3/40, 7/16, 3/4 & 1/2).
The other problem was with the Exam-style question at the end of the section. He got a & b correct, but for c he got 0.09, and the answer is printed as 0.18.
I would never have questioned the answers printed in a maths book until we started using this one - but there have been previous errors, which even I can see, so that is why I am asking this time, as Probability is a subject that I have no knowledge of, and I'm sorry to say very little desire to learn - I loved trigonometry and geometry, and I am even inclined to re-learn my algebra when we get to the nitty gritty of the next unit, but I find it so hard to get my head round probability!!
He does seem quite capable of understanding this subject, and all of his other answers are correct - apart from silly errors when he's lazy, but he has checked and re-checked these ones, so that is why I thought I'd call in an expert! If the book is right and he's wrong, then we do need to get some extra help, which I am happy to do.
Thanks again.

3. ### iron6000

Hi,
Those answers for Assess 9 Q4 - your son is spot on and the book is wrong. It's quite common for some book answers to be wrong as others have said, just hopefully not too many!
The answer for Exam style question is correct.
He has probably forgot to consider that there are two orders possible, Hassan passes and Louise fails (0.9 x 0.1 = 0.09) or Hassan fails and Louise passes (0.1 x 0.9 = 0.09) and as these two events are mutually exclusive (cannot happen at the same time) you can add them to achieve the overall probability of one person passing and person failing (0.09 + 0.09 = 0.18).
Hope this helps and do not worry about your "lack" of knowledge of Statistics, many a fully qualified teacher is very uncomfortable with Statistics as it is such a different discipline to Mathematics.
I would always recommend all students to do as much statistics as possible though as that it where the world is heading!
Cheers!

4. ### KarvolOccasional commenter

It is not a different discipline to mathematics, but another discipline of mathematics.

5. ### iron6000

Yes, perhaps I should have said "such a different discipline to the rest of Mathematics". Throughout my career I have found that this area is one of real concern to many colleagues and even some GCSE topics are not well understood by a proportion of well-qualified teachers. That is not meant as a criticism - just an observation.

There was very little probability in O-level (at least the board I did, but I suspect it was not alone) and many people did no stats at A-level, which may explain things with some of the over 40s - perhaps particularly those who have come into teaching maths as their second subject.
I once set a particularly nasty probability homework, saying "do not leave this until the night before it's due, as your parents are unlikely to be able to help you on this one if you get stuck, even if they can normally". I was thinking to myself "and that includes you whose mother teaches in this department" - and indeed, a day or two later, she consulted me because she'd been unsure. (She didn't teach Higher tier.)

7. ### Goretti

LOL! Shucks, trust a maths teacher to have worked out that my age is well over 40! I stopped boasting to my son that I'd taken my maths O'level early (the teacher put me into the early [November] group after my Dad told me to go to the staff room and tell them I was NOT going to stay in the CSE group which I'd been put into - he thought CSEs counted for nothing) when I realised that that just meant that after I'd passed it (with a B, so my Dad was right about my ability) I never did any maths again (Fine Art MA I'm afraid) and that's a LONG time of not using it. The fun has been in re-learning maths with my son - all those patterns in numbers we were never taught - Fibonacci, never touched it at school, and yet so Beautiful! But statistics - well, I do draw the line at those - especially as they are so easily manipulated by some...;-)

8. ### Goretti

Thanks again - he realised straight away what he'd missed, when I said that you are supposed to look at this two ways. If I could be certain that the book was right I would have made him go through it all again to see where he was going wrong!
It is tricky when one knows there are some errors, I suppose I could get him to do a probability check to see whether the next answer given would be right or wrong lol!
Regards!