first find the mean of these numbers can you do that?
add them all up and divide by 10
82 is what I got
yes you are right
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
90 - 82 = 8 and so on
75=7 80=2 90=8 95=13 75=7 85=3 55=27 80=2 90=8 95=13
right strictly it should have been 80 - 82 = -2 but its not that important because we square each of those results
so now we square ach of the 10 results 7^2 = 49 2^2 = 4 and so on
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
use your calculator - it would be a bit long winded otherwise. It a bit long winded anyway!
in the formula x is a number , mu is the mean and N is the total numbers.
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
the biig 'E' means 'the sum of'.
right i got that too so std dev = sqrt 131
I'm confused on how to do the equation
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
correct is |dw:1438979612906:dw|
the STd dev comes to 11.45 correct to decimal places
Is that the answer? Sorry, math is my weakest subject.
yes the variance is 131 the standard deviation is the square root of the variance
standard deviation gives a measure of the spread of the data
Oh, ok that makes sense
good the lower the standard deviation the closer the data is the mean . If the Std dev is high it means there is a lot of values far away from the mean