Question

standard deviation
2. The temperature in the given problem are averages for the months of March, June, September, and December. Calculate the mean and the standard deviation for each.
Laoag City 54deg 51deg 62deg 52deg
Baguio City 40deg 75deg 75deg 36deg

in laog I got 54.75 for the mean I just get the average
is the mean correct and how will I solve the standard deviation???

Answer 1

@apoorvk

Answer 2

Yes, you 're right in case of Laog - mean is just the average.

Answer 3

@apoorvk
but how about standard deviation

Answer 4

Yeah I'll show you that - any idea what standard deviation is?

Answer 5

it is the square root of the Variance.
but there are other formula I dont know what will I use

Answer 6

Okay yes. so.
variance --> variance is "mean of sum of square of terms" minus the "square of mean of terms"

Answer 7

Confusing?
Okay lets say that the a data has 3 terms --> a, b, c.

"mean of sum of square of terms" means ---> (a^2 + b^2 + c^2)/3

"square of mean of terms" means ---> ((a+b+c)/3)^2

so, Variance = V = (a^2 + b^2 + c^2)/3 - ((a+b+c)/3)^2

Answer 8

Helps?

Answer 9

could you explain it further

Answer 10

the first thing means that --> you square each term, add them up, and then take mean.
the second thing means --> taking the mean, and then squaring.

Answer 11

I got confused about population standard deviation and standard deviation,

Answer 12

Okay let me write it this way, if it helps to visualise better:

A data has 3 terms --> a, b, c.

\[\text{"mean of sum of square of terms" means --->} \frac{(a^2 + b^2 + c^2)}{3}\]

\[\text{ "square of mean of terms" means --->} (\frac{a+b+c}{3})^2\]

\[\text{so, Variance = V =} \frac{(a^2 + b^2 + c^2)}{3} - (\frac{a+b+c}{3})^2 \]
\[\text{and, Standard deviation = }\sigma = \sqrt V \]

Answer 13

I got the answer of 4.3329 but I got confused about population standard deviation and standard deviation,
look at this http://easycalculation.com/statistics/standard-deviation.php

Answer 14

I got the answer of population standard deviation

Answer 15

What do you do in that?

Answer 16

I just got confused about population standard deviation and standard deviation when I enter the given data, because I dont know which of the two is correct

Answer 17

population std. dev.? Where is population coming into this? This question is about temperatures right?

Answer 18

yup,

Answer 19

I tried your formula but I got the population standard deviation

Answer 20

population? where does population come into the picture?????

Answer 21

Or is that some other formula?

Answer 22

http://easycalculation.com/statistics/standard-deviation.php just scroll down
in this link I type the given
when I used the formula you gave I just got the population standard deviation

Answer 23

i think @Chlorophyll has a better idea about this - He will help you onwards on this problem. :)

Answer 24

@Chlorophyll any Idea plz.

Answer 25

By the way thanks @apoorvk for the time , it is a great help indeed

Answer 26

See, you just square each term of the data. then add them up. then divide the sum by the no. of terms. and then deduct the mean from it.

that will give you the variance. sqrt of that is std. dev.


hope this is simpler and lucid now. :)