Dekoyl's question thread

[shinny]

ummm

it's possible.

for TI-84 series and TI-83+ (dunno about the other ones)
the following functions are probably found in MATH

integral of a function [graph starting at (0,0)]

Code: [Select]

y1=fnInt(...function here...,X,0,X)

and

derivative of a function

Code: [Select]

y1=nDeriv(...function here...,X)


Doesn't seem to be working on my 84 =\

[dekoyl]

Unfortunately, me too.
I don't recall sketching graphs of derivatives etc. on my calculator. I just assumed that it's possible.

[Glockmeister]

sorry... i shouldve explain myself better

the ti-83 dont have a good capacity to graph integral or derivative functions. It would probably be faster to dervive the function and then graph, unless theg function is quite an esoteric function

[ell]

Just to confirm, Mao's method does work. This is on my old TI-83 btw.

edit: to get the derivative graph to work try type instead:

Code: [Select]

y1=nDeriv(function,X,X)


[Glockmeister]

heh... i never use that thing not now i have my ti-89

[shinny]

Just to confirm, Mao's method does work. This is on my old TI-83 btw.

The integrals are working for me, but the derivatives aren't.

[ell]

heh... i never use that thing not now i have my ti-89

oh you got one! I remember a while ago you were talking about how you should get a CAS... welcome to the club

@shinjitsuzx: check my edited post

[Glockmeister]

heh... i never use that thing not now i have my ti-89

oh you got one! I remember a while ago you were talking about how you should get a CAS... welcome to the club

@shinjitsuzx: check my edited post

yeah the impetus was that someone has stolen my ti84 calc, so i brought a new one. funnily enough the cas calc cost more than the non-cas

[shinny]

heh... i never use that thing not now i have my ti-89

oh you got one! I remember a while ago you were talking about how you should get a CAS... welcome to the club

@shinjitsuzx: check my edited post

Ah right, yeh it's working now. Ta.

[dekoyl]

Thanks guys. I got it working.

[dekoyl]

No one I've asked in person can work this out.

Out of people attending a local gym, 10% are underweight, 20% overweight, 15% obese and the rest have normal weight. Underweight people on average weigh 3kg less than their ideal weight, people within the normal weight range weigh on average 4kg more than the ideal weight, and overweight and obese people have 12 and 18kg extra weight respectively. The standard deviation of extra weight on the patrons of the gym is..?

Mao? dcc? Coblin? /0? Shinjitsuzx?

Oh and nearly 800 views and only ~6 different people have replied in this thead. Weird.
Can any of you non-contributors work it out?
I see you guys looking at my thread. I'm always aware. Always. 

[Mao]

E(x) = 0.1 * -3 + 0.55 * 4 + 0.2 * 12 + 0.15 * 18 = 7

E(x²) = 0.1 * 9 + 0.55 * 16 + 0.2 * 144 + 0.15 * 324 = 87.1

now, remembering that var(x) = E(x²) - (E(x))² = 87.1 - 49 = 38.1

then, sd = var^1/2 = 6.17

Oh and nearly 800 views and only ~6 different people have replied in this thead. Weird.
Can any of you non-contributors work it out?
I see you guys looking at my thread. I'm always aware. Always. 

oh, relax.

[dekoyl]

oh, relax.

Yes, yes I am.

E(x) = 0.1 * -3 + 0.55 * 4 + 0.2 * 12 + 0.15 * 18 = 7

E(x²) = 0.1 * 9 + 0.55 * 16 + 0.2 * 144 + 0.15 * 324 = 87.1

now, remembering that var(x) = E(x²) - (E(x))² = 87.1 - 49 = 38.1

then, sd = var^1/2 = 6.17

Ah thanks Mao. It looks very simple now.

[dekoyl]

I can't believe I'm asking this.
is equal to:


or

I can get both answers (unless I got my log laws wrong which is very disturbing.)

Thank you.

[Collin Li]

Letting





(Sorry, I never remember the change of base law, so I do it manually)



Note: you can't take the out unless you take the 'th root of 4.