Question

Find the population standard deviation (σ not S) for the data set: {75,80,90,95,75,85,55,80,90,95}
Round your answer to the nearest 10th.

Answer 1

first find the mean of these numbers can you do that?

Answer 2

no

Answer 3

add them all up and divide by 10

Answer 4

82 is what I got

Answer 5

yes you are right

Answer 6

now you need to find the difference between each number in the list and 82

so for first number 75 it is 82 - 75 = 7
for 80 it is 82 - 80 = 2
do this for all the other numbers

Answer 7

90 - 82 = 8

and so on

Answer 8

75=7
80=2
90=8
95=13
75=7
85=3
55=27
80=2
90=8
95=13

Answer 9

right strictly it should have been 80 - 82 = -2 but its not that important because we square each of those results

Answer 10

so now we square ach of the 10 results

7^2 = 49
2^2 = 4
and so on

Answer 11

when you have done that add them all up
then divide the answer by the number of values (10)
this result is called the variance
find the square root of the variance to get the standard deviation

Answer 12

use your calculator - it would be a bit long winded otherwise. It a bit long winded anyway!

Answer 13

in the formula x is a number , mu is the mean and N is the total numbers.

Answer 14

75=7^2=49
80=2^2=4
90=8^2=64
95=13^2=169
75=7^2=49
85=3^2=9
55=27^2=729
80=2^2=4
90=8^2=64
95=13^2=169

1310 divided by 10=131

Answer 15

the biig 'E' means 'the sum of'.

Answer 16

right i got that too
so std dev = sqrt 131

Answer 17

I'm confused on how to do the equation

Answer 18

mu is the mean
x - mu is the differences
oops sorry i made a mistake with that
- the formula is just a summary of the process
you have to go through the procedure as we did

Answer 19

correct is