BEC'S methods questions

[Mao]

The weight of a colony of penguins follows a normal distribution. 80% weigh more than 100kg, 10% weight less than 70kg. Find .

penguins, penguins

the units for the above two should be "kg", not penguins

[bec]

The weight of a colony of penguins follows a normal distribution. 80% weigh more than 100kg, 10% weight less than 70kg. Find .

penguins, penguins

the units for the above two should be "kg", not penguins

ahahhahaha

[Mao]

To weigh over 120kg:

normcdf(120,1E99,157.334,68.123)=0.708

hence, the probability of between 30 and 50 penguins (assuming you have 50 or more to start off from)

y1=binomcdf(x,0.708,30,50)

go into table and find the first case greated than 0.65 (which incidently, happens to be 44, so didn't think the question through, DivideBy0 , or I've gone terribly wrong somewhere)

[bec]

To weigh over 120kg:

normcdf(120,1E99,157.334,68.123)=0.708

hence, the probability of between 30 and 50 penguins (assuming you have 50 or more to start off from)

y1=binomcdf(x,0.708,30,50)

go into table and find the first case greated than 0.65 (which incidently, happens to be 44, so didn't think the question through, DivideBy0 , or I've gone terribly wrong somewhere)

"Go into table"? What do you mean?

[ReVeL]

Press 2ND then TABLE, perhaps? (TABLE is the same button used for GRAPH, top right)

[bec]

Yeah, I tried that but my table only has one column: "x".

I checked to see if I could store it to l1 (which is the name of a column in my stat/list editor) but all that achieved was deleting the l1 column.

So now I have two questions:
1. How do you get the L1 column back...
2. How do you use a table to find "n"

Thanks

[Mao]

yeah, ReVeL is right

however, this only works if you have a TI-89 or above.... 84 chokes when you make binomcdf a function of a variable (x)

I'd have no clue how a 84 would do this...

[PS, for the time (I'm so bad at remembering these things), bec, do you do CAS? ]

[bec]

[PS, for the time (I'm so bad at remembering these things), bec, do you do CAS? ]

Yeah I do CAS. So why is this table thing not working for me? How should I set it up?

[Mao]

in the Y editor, put y1=tistat.binomcdf(x,0.708,30,50)

now green F5, and there should be a x column and a y1 column... that should just work.

if it doesnt, go into Green F4 (TBLSET), and check if "Independent" is on, if so, set it to AUTO. Graph <-> Table should also be OFF.

[bec]

I did all that before, and it didn't work.
Is there another method I could use? My teacher never mentioned this (hence me not realising that my calc isn't set up to do it until today). But I also can't remember doing a question like this before, so I don't think I've been taught/read about another method either...

[Mao]

I did all that before, and it didn't work.
Is there another method I could use? My teacher never mentioned this (hence me not realising that my calc isn't set up to do it until today). But I also can't remember doing a question like this before, so I don't think I've been taught/read about another method either...

it'll be highly unlikely for this question to be asked on an exam, but its better to get the calculator set up anyways. Other methods of solving this can be very tedious, sooo...

I'm not sure what you see in the Y= screen or the TABLE screen, screen-captures would be helpful.
But otherwise, I'd suggest a calculator reset (this means you will have to load the TISTAT application found from the CD), do this by taking the batteries out (inc the small backup battery) and wait a few minutes, then put everything back in place. You should see an "Installation in progress, do not Interrupt" thing come up.

[bec]

That's so frustrating - I bought this calculator 2nd hand so I don't have the cord or the CD. I could get it from a friend but I think I might just wait till I get back to school, see if my teacher can help me.
Thanks for the help anyway mao

[Mao]

the cord is fairly generic, most digital cameras uses the same cord.
stuff on the CD can be found on the website http://education.ti.com/educationportal/downloadcenter/SoftwareList.do?website=US&tabId=1&paneId=4

connectivity software: http://education.ti.com/educationportal/downloadcenter/SoftwareList.do?website=US&tabId=1&paneId=7
you want TI-Connect

[bec]

Wait, I got it! I wasn't putting it in the Y= editor...I really need to learn to read...

in the Y editor, put y1=tistat.binomcdf(x,0.708,30,50)

now green F5, and there should be a x column and a y1 column... that should just work.

if it doesnt, go into Green F4 (TBLSET), and check if "Independent" is on, if so, set it to AUTO. Graph <-> Table should also be OFF.

Thank you so much for trying to work it out for me even though you already had and I hadn't noticed.....!

[Mao]

lol
no worries