This from a young lady in Malasia.
I'm mathematically challenged
Folks, it is confirmed. I CAN'T do maths to save my life.

I had a few questions thrown my way today and as I attempted them, I realize how much, or rather, how little I know or can remember solving mathematical questions. SIGH. Here are some samples. Can you solve them?
The total cost for five items of repair work on a car was $195. Overhaul of the carburetor cost twice as much as the tune-up, brake pads cost one-third as much as the carburetor overhaul, and alignment and wheel balancing each cost one-third as much as the tune–up. What did the tune-up cost?
A certain preparation consists of liquids x, y, and z in the proportion 5:2:1. How many gallons of the preparation can be made from a stock of materials consisting of 25 gallons of x, 20 gallons of y, and 8 gallons of z?
The normal selling price of a case of soap is $10.00. During a special sale, the price was reduced by 10%. (Note: 10% means 10 percent.) This sale price was 20% greater than the cost to produce a case of soap. How much did it cost to produce a case of soap?
Alice's Action Plan: Borrow younger brother's maths book, start revising and attempt questions! at 9:18 PM Folder(s): Ramblings, Reflection
10 commented:
cleomy said...
You are not alone... you know why? in fact majority of Msians are just like you CAUSE the Questions are all in ENGLISH!!!

If they're in BM like "Satu ayam jantan bersetubuh dengan dua ayam betina, berapakah ayam hampsum yang telah terlepas dari tangan si pencuri?"

See what I mean? suddenly all makes sense if the questions are in BM!!! So blame on our parents for sending us to Malay medium speaking school
Thursday, May 17, 2007 Alice Teh said...
Hmm... that's like blaming the system, Cleomy. However, it does seem like a reasonable explanation.

I don't, for some reason, remember the concept behind all these maths problems. I do, however, understand why most of your thinking, in this case the example you provided in Malay, is adult in nature. I will not put the blame on you for we, after all, are humans. Totally understandable. :P
Friday, May 18, 2007 Anonymous said...
1)$45
2)5
3)$7.50
Friday, May 18, 2007 anthropositor said...
Dear Alice,
I am an unschooled old man who escaped from home very young. While I got most of my education in libraries and used book stores I was, before my stroke unusualy bright. I was once in Mensa and I have taught competitive chess for fifty years.

I am sorry to say I am ignorant of your native language so I am not sure of everything cleomy had to say, but I expect that she is at least in part, wrong.

While Anonymous's answers were technically corect, he, she or it was being a show-off, and was actually destructive to you.

While I cannot tell you anything about the formulaic style your instructor may require, uschooled as I am, I can tell you how to sort these matters out logically and experimentally. To my mind, that is at least as useful as math.

In the first and most complicated problem find out what you know and put it in some sort of logical order. You know the
Total cost=$195.
Carb cost 2x Tune=? (Biggest).

You know the smallest things are the Wheel Bal. and Align. and they are equal to each other.

So the Brakes and the Tune come somewhere in the middle.

Pick some kind of reasonable number for Tune and try to work the problem. Using $40, Carb would be $80 BUT 1/3 of that would give weird numbers with decimals, so you know they are wrong. STOP.
Pick a larger number, say 45 for Tune. Now try it again.
If Tune is $45 Carb must be $90.
Brake is a third of Carb for $30.
And Wheel Bal and Align must be $15 each. And you solved it without any algebraic nonsense. Now it should be fairly easy to put the answer in whatever algebraic form your instrucor requires. But always double check your answer. 45+90+30+15+15=195.

Now we go to the easier ones. You want to know what quantity of a solution of known proportions can be made from known stocks of chemicals. Either X,Y, or Z is going to be the limiting factor and will supply your answer. With unlimited Y and Z you could make five gallons with your known X.

With unlimited X and Z you could make ten gallons with your Y supply.

With unlimited X and Y supply you could make eight gallons with the Z supply.

The smallest number is your limiting number so you can produce 5 galons with your supply on had and you have leftovers of Y and Z when you are done.

And in your last problem you are staring with 10, reducing it to 9 and then saying 1.2 times "what" equals 9.0. Fill in 7.0 for
"what" and the answer is too small. Fill in 8.0 and the answer is too big. Soon you will discover 7.5 hits it on the head.

Learning to think with a certain logical precision may be even more useful than learning the "rules" your math teacher is trying to pump into the class. But do your best to pretend you did it his way. Your grades will be better.

Good luck to you dear. I think you are going to do just fine.
Anthropositor

Alice Teh said...
Dear Anthropositor,

Thanks very much for your comprehensive and detailed answer. Reading it through gives me a much clearer picture, especially using logic to derive at the answers. I have never thought of solving them this way. Plus they were multiple-choice questions and the answers were staring back in one of the choices given! Great thinking! Thanks for sharing. I really, really appreciate your input.

Doing maths is a humbling experience for me but not all is lost because now I have gained a new way of looking at things. It may be there all along, but just wasn't consciously paying attention to it.

Thanks again! You're a great teacher.