math question (daughter needs help)

tarsier said:
Allow me to correct one misconception. Many people believe that pie are squared. Wrong! Pie are round.
Click to expand...

Sorry to contradict you but if I'm around then Pi r E10

:rolleyes:

Kane
 
Point44 said:
Higher degree maths is actually quite similar. Normal maths, not algebra. You just need the ability to approach the question in smaller steps to understand it. Although it's not just addition and subtraction. There's stuff like triple integration. ALGEBRA ON THE OTHER HAND IS JUST PLAIN STUPID. I NEVER PASSED ALGEBRA. Couldn't get my brain to understand it. The module i did in university just consisted of equations of greek alphabets and proving it. It just didn't make sense. I still have the workbook and have been trying to sell it on amazon but nobody wants it.
Click to expand...

Algebra is the math :)
 
It is really amazing--the fear of mathematics that people have. Several years ago, I taught a course in statistics for first year medical students. A grade of 70 was required to go on to second year--meaning, you fail, and it will cost you big time. The exams were a series of problems to be analyzed. The student were allowed to bring with them a calculator and 1 normal-sized sheet of paper on which could be written anything they wanted: formulae, whatever.

Several time I saw students crying during the exam because they were sure they were going to fail. (Some did fail.) But many times I would walk over to them, look at their notes and say: "Listen very carefully to me. You have everything that you need to pass this exam with a mark of 100. Calm down, think about the problems as if they were homework. (I gave a lot of that. :D ) You wanna be a doctor? then you need to develp a sense of proportion. This isn't scary, compared to what you will end up doing if you get through medical school."

Overcoming math block was the hardest thing that I had to teach in that course.
 
Shaldag yes it is amazing ! I did take lots of math in high school and college and the only thing that really confused me were transforms like the Fourier. I asked my math ace brother one time to explain .I responded that 'you mean you can't solve it here on earth so you take it to the moon ,solve it there and bring it back ?' He said exactly !!!
 
Mete, if you were doing Fourier transforms in high school-- what did you do in University?

As an historical aside, my statisitics teacher (RIP) invented the Fast Fourier Transform (at a time when computer time was quite expensive) as a practical alternative to the Discrete Fourier Transform. The legend is that he and his coauthor came up with the idea while folk dancing. The reference for the paper is:

James W. Cooley and John W. Tukey, "An algorithm for the machine calculation of complex Fourier series," Math. Comput. 19, 297–301 (1965).

sorry for the thread hijack.
 
Esav Benyamin said:
"Here is a cylinder. The formula for the volume of a cylinder is pie r2 height. What is it's height? The diameter is 22.5 centimeters. The mass is 45.4 grams and the density is .13 grams per cubic centimeter."

V = PI times R square times H

V = 45.4 gm divided by .13 gm/cm cubed = 349.23 cm cubed
PI = 3.1416
R = 22.5 diameter divided by 2 = 11.25
R squared = 126.56

349.23 = 3.1416 times 126.56 times H
349.23 = 397.61 times H
349.23 divided by 397.61 = H
.88 cm = H
Click to expand...

I was just wondering how accurate they require her answer to be. Since Esav uses Pi as 3.1416 (Pi = 3.14159265...) then it is accurate to approximately 4 significant digits but if she used a calculator she'd probably get closer to 7 or 8 significant digits so it would be more accurate. They would both be correct, of course, but I guess you could say that one would be more correct than the other. Accuracy has been a big topic in my math courses, especially a Numerical Analysis course I took in college. I learned to appreciate accuracy. :)
 
doesn't matter. she's only got two sig figs in the density, so whether she's got 5 or 50 in pi, her answer should only have two, and those two will be the same either way.
 
V = PI times R square times H

V = 45.4 gm divided by .13 gm/cm cubed = 349.23 cm cubed
PI = 3.14159265
R = 22.5 diameter divided by 2 = 11.25
R squared = 126.56

349.23 = 3.14159265 times 126.56 times H
349.23 = 397.599965784 times H
349.23 divided by 397.599965784 = H
0.87834514600970200167998915865822 cm = H
 
I was just wondering how accurate they require her answer to be.
Click to expand...

In many engineering courses one lost points if the answer was given more accurately than the least accurate starting value.

TLM
 
Since my primary exposure to mathematics, as an American capitalist, is dollars and cents, I tend to round everything to two decimal places unless instructed otherwise. :D

And I agree that the most important factor here is that Pi r E10.
 
Ha, ha. Yeah, I guess I should've trimmed that last number down, huh! :) I was giving a test in class and did it in a hurry.
 
I hate solving math eqations myself. I barely got throgh math classes in high school, but everything else I was pretty good at.
 
Rather than solving the problem for her you should give her a hint, like:

"You can use the mass and the density to figure out the volume, then if you know the volume and the area of the base you can figure out the height, remember that the volume is the area of the base times the height".

If this is not enough you can help her to set up the equations and let her solve for the unknown variables.

The point is don't solve it for her, let her think.

This reminded me of an old joke:

A kid is asked about how to use a barometer to obtain the height of a building, he says:

"You can tie a long string to the barometer, go up to the roof and let it hang until it touches the ground, then measure the length of the string needed. Or take a stopwatch, drop the barometer form the roof and measure the time it takes to hit the ground, then calculate the distance traveled using the time and acceleration constant. Or locate someone who works in the building and offer to trade a barometer for a set of plans".

Luis
 
Ravaillac said:
If "higher maths" means something like "high school maths" you're completly right. If not you're wrong. Try some algebra, and you'll see these are use less.
Click to expand...

Algebra is nothing but adding, subtracting, multiplying, and dividing.

I have my fancy calculator right here. Let's look at its features:

Y^X that's just multiplying Y by Y by Y... X times, just multiplication

X^2 that's just a shortcut for multiply X by X.

10^X that's just multiplying 10 x 10 x 10... X times, just multiplication

e^X that's just Y^X except you substitute e for Y... Just more multiplication

% is just multiply Y times X/100. It's just multiplication and division.

Delta % is a (Y x 100) / X, must more multiplication and division.

1/X is just divide 1 by X, pure division.

SQRT X is just multiplication and division.

X! is just 1 x 2 x 3... x X, just multiplication.

SIN, COS, TAN, SIN-1, COS-1, TAN-1, ARCSIN, ARCCOS, ARCTAN, HYPSIN, HYPCOS, HYPTAN, etc. These are just table lookups. But, the numbers on those tables are arrived at by multiplication and division.

Log, LN, LOG-1 are, again, just table look-ups and the numbers in the tables were arrived at by mulitplication and division.

What else is there?

Most computers can't multiply or divide muck less take the cube root of a number. Yet computers handle most of our math, even algebra, calc, diff eq., stats, non-linear stuff, all of it. How can computers do all that? Simple, they can add and subtract and multiplication and division are just repeated addition and subtraction. So, really, all math comes down to add and subtract.
 
and the Ark came to rest...
Noah said to all the creatures in the Ark: "Go forth and multiply!"

However, the adders said to Noah: "We cannot multiply, we are adders."

Noah cut a tree into logs, and made one of the logs into a table. He presented the table to the adders and said: "Now go forth and multiply. Even adders can multiply if they use a log table."





:D
 
Shaldag, I'm not sure when the transforms came in .I had 4 years of math in high school and three in college.I had it all,geometry , solid geometry, algebra,transforms, etc, etc!!!! I even had a computer course in college 'in the old days' when if you didn't write the program properly and ended up asking the computer to divide by zero it would try and try until it had a nervous breakdown and blow fuses ! The computer often took data from another program and put it into yours .
 
Mete,
your description of your education and the divide errors are dating you, big time!
 
mete said:
Shaldag, I'm not sure when the transforms came in .I had 4 years of math in high school and three in college.I had it all,geometry , solid geometry, algebra,transforms, etc, etc!!!! I even had a computer course in college 'in the old days' when if you didn't write the program properly and ended up asking the computer to divide by zero it would try and try until it had a nervous breakdown and blow fuses ! The computer often took data from another program and put it into yours .
Click to expand...

Did that happen to be Fortran? If you get the equation in a loop the computer will just hang. I had to do that in my Actuarial Science Degree, i don't know why we did computer programming but we did.

I think throughout the degree probably the worst subject was Statistic and Probabilistic Modelling for Insurance. It was a nightmare. Sometimes students will just not bother going to lectures 'cos nobody understood anything. However, there was this one whizz kid who always sits at the back with a baseball cap and never participates in class at all. Turns out he had something like a 98% average for all 3 years. And i think the university kind of paid for his second year and third year or something like that.

For me there are certain things that i can never get my head through. Mechanics and algebra. I can do probability theory, statistics and most of the other stuff but even simple high school mechanics is kinda difficult for me.

Right now i'm just getting away from advanced maths which is why i did forensic science. That was great. No maths. Loads of chemistry and playing with cool machines.
 
You must log in or register to reply here.
Back
Top