ECMT1010 Computer Ass. 2 (1 Viewer)

[stazi]

Hey, when did we learn how to use the NORMDIST and NORMNIV functions in excel? In our last comp workshop, we simply did a random number thingo.

 

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[stazi]

Ok, this isnt making much sense.
Could someone please just explain what we need to use for Q1?

Random number excel thingo?
PHSTAT Normdist thing?
=NORMDIST(X,Mean,StDev,Cumulation)?

It feels like I'm doing something wrong, because:
(i) P(X>750) = 1 - ((P(X>750))
So, we transform it to the standardized Z value:
Z = X-mean/stdev
Z = 750-520/96.3
Z = 2.39 (rounded to 2 d.p.)
P (X<750) = 0.9916
P (X>750) = .0084

However, if we use excel:
=normdist(750,520,96.3,true)
=0.991538345
This is close to the Z table in our blue books, but how do we say that were looking for the probability for X>750, not less??

And if we use phstat
... just realised that it's correct
But why isn't excel right. We are after all asked the normdist function.

 

[stazi]

also, how do u change the number of decimal places?

 

[stazi]

P(X<560)
"=normdist(560,520,96.3,TRUE)"
0.6611


same thing here. answer should be 0.6628

 

[stazi]

Not getting any replies, but I'll post the excel answers and solutions done manually so you can see that they differ. I'm pretty sure I'm doing everything right

 

[04er]

Hey 1Time4ThePpl sorry I haven't even looked at this assessment When is it due?

 

[stazi]

its due next week.

 

[stazi]

Here's question 1. b.
The excel answer (although I'm not too certain if im using the function correctly) again differs from the manually worked out answer

 

[Cavalier87]

hi mate, was waiting for a thread like this
i seem to be getting different answer to you
so are we suppose to use the excel function because im using phstat2

 

[stazi]

well its asking us to use the NORMDIST function. so i wouldnt say that phstat is appropriate, as phstat doesn't have that function. You can work out the answer, but just not by typing =normdist
I also checked with the lecturer, and he said the answers are just different, because excel uses a more mathematic way of working it out. As long as the dif isnt massive, they are correct.
And for the first one, we just do =1-(cellnumber) after working out the initial normdist function .

 

[absolution*]

Ill post my answers tomorrow night. I expect to be finito by then.

 

[stazi]

splendid then we can compare them. and play scrabble.

 

[s.m.i.t.h]

how do you do question 2 using excel?
please help!

 

[stazi]

s.mith, doing it now, will post up how i did it soon. although im confused as to how the hell i do the stdev and variance

 

[stazi]

ive got a feeling some of this (b and c) may be wrong, as it seems a bit too easy.

 

[s.m.i.t.h]

with question 3 part b) hasnt the variable compare been createed for us already?
although the question states 'create a new variable, compare=con/city'?

 

[sarevok]

yep, it already has. pretty stupid.
q3 is quite tricky.

 

[stazi]

apparently my q2 is correct according to my tutor

 

[ressul]

How about Q3?

What's the differnce for a). I could only say that the means are increasing, nothing else.