Stats help:
Q.The mean of 12 observations is 3704.One more observation is added and the mean becomes 37.5.Find the value of new observation.

- uri

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- anonymous

You can do it!

- anonymous

Find the total of the operations when there were 12.
Then find the total when there were 13.

- anonymous

What is the difference?

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## More answers

- anonymous

Since \[
Average = \frac{Total}{Observatioins}
\]Then \[
Total = Average \times Observations
\]

- anonymous

find the sum
\[\sum x_i=
\bar{x}n\]

- anonymous

\[MEAN x=\frac{ \sum_{}^{}x }{ n }\]
total of 12 observations=37.06*12
total of 13 observations=37.5*13
13th observation=? (subtract and find)

- anonymous

lets call the new observation x
\[\bar{x}_2=\frac{\bar{x}_1+x}{n+1}\\\bar{x_1}=37.06,\bar{x}_2=37.5,n+1=13\]

- uri

I solved the whole question with LatEx and it crashed....

- anonymous

i mean\[\bar{x}_2=\frac{\bar{x}_1n+x}{n+1}\]
\[x=n(\bar{x}_2-\bar{x}_1 )+\bar{x}_2\]

- uri

I know..I was doing it myself but the page crashed..

- uri

I so pissed off right now..

- anonymous

so you cant see anything in LaTex here

- uri

I know how to do this..i was typing it if i was write.I was at the end of it and it crashed....

- anonymous

ohhhhh bad...okay ...it does that sometimes ,i guess it has to be reported to the OS feedback

- uri

Let me do again..oh well.

- uri

Formula is
\[\bar{x} =\frac{ \Sigma x }{ n } \]
where n=15
and \[\bar{x} =3704\]

- uri

So,plugging in the formula
\[3704=\frac{ \Sigma x }{ 12 }\]

- uri

I mistyped above n=12.

- uri

Then,
\[\Sigma x =4448\]
let the value of one observation added be *y*
Using the same formula again
\[37.5=\frac{ 4448+y }{ 13 }\]

- uri

\[487.5=4448+y\]
\[y=4448-487.5\]
y=3960.

- uri

3960.5*

- uri

@wio Help me c:

- anonymous

What did you get for your totals?

- uri

What do you mean?

- anonymous

is it 37.04 or3704

- uri

3704.

- anonymous

\[
12\times 3706 = ?\\
13\times 37.5 = ?
\]

- uri

@wio it's 3704* and
12 x 3704=4448
and 13 x 37.5 =487.5

- anonymous

didnt you mean 37.06 or 3706

- anonymous

as you have calculated it should b e y=487.5-4448
which is negative

- uri

Omg sorry i typed wrong,Let me edit the question..Sorry :3

- uri

@surjithayer we subract the small number with the greater one...No?

- nincompoop

kick your computer

- uri

@nincompoop not my computer's fault something is wrong with OS.Happend to many users.

- anonymous

i think total for 13 observation should be greater than total for 12 observations

- nincompoop

start doing paid subscription :)

- uri

I don't think so @surjithayer because the other question i did at my class with my teacher the total for 16 observation was quiet less than the observation for 15..

- nincompoop

uri, this is the same kind of help you received earlier.

- uri

your point?

- nincompoop

you should be able to do this one if you understood the other one :P

- uri

So,didn't i just do it? I'm asking if i'm right..problem?

- nincompoop

you had 6 earlier, now you have 12
then 1 is added on both that gave a new mean

- anonymous

o.k if total for 13 observationis less then 13th observation should be negative

- nincompoop

(444.48+x)/13=37.5
here's how it is broken down without the fancy statistical jargon
37.04 x 12 = 444.48
multiply it back so you get the summation prior to the unknown. since there were 12 observations, you multiply your initial mean by 12.
now we need to find out the unknown (that is +1 observation) in order to get the mean of 37.5.
so that is 444. 48 + x
then divide it by the final number of observations, 13
(444.48 + x)/13 = 37.5

- uri

Nin it is 3704 not 37.04..

- nincompoop

I think that's a typo LOL
but if it is really 3,704 then the same kind of process is required for you to find the unknown observation

- uri

Let me ask a friend

- nincompoop

okay. it is weird that the new mean is wayyyyyyyyyyyy too low than the initial one. from thousands to tens

- uri

LOL NIN IT'S 37.4 NOT 3704.My sir doesn't know how to make a decimal point.He wasted my 1 hour..

- nincompoop

lol told you so… my training in chemistry paid off

- uri

Omg now i know how to do it..xD

- anonymous

then it is 37.5*13-37.4*12

- uri

Let me solve and show. :P

- nincompoop

yeah so I put 37.04, you just have to make the correction to 37.4

- uri

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- uri

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- nincompoop

you're on the right track

- uri

Thanks :D

- nincompoop

always ask your professor what he has written down so you're not wasting a lot of time calculating the wrong information.

- nincompoop

everyone makes mistakes

- uri

I do that.I joined late and my class fellows have done this already i just took these photocopied questions from a classmate and did few at class..so didn't know that my teacher makes such a weird typo like WEIRD..0 except a decimal point.

- uri

@nincompoop look xD

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- nincompoop

lol
now you know that small circle is period

- uri

Lol yess

- anonymous

there is small circle on is also .you can corelate

- anonymous

any way you know the procedure to solve such problems.

- uri

:)

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