Question

Class A Class B Class C
80 72 100
85 90 90
87 85 94
92 84 100
86 91 75
90 78 30
94 94 94
100 86 72
75 82 85
45 78 87
85 86 42
38 78 100
72 95 90
94 90 94
62 88 60

Answer 1

@marissalovescats

Answer 2

i need the standard deviations of a and b,

Answer 3

You asked me to help you with Algebra 1 lol

If this is statistics I'm not sure how to do standard deviations.

I know there's a formula for it but I'm not sure how to use it.. So I'll see if @jim_thompson5910 can help you

Answer 4

ok lol thanks anyway, and yea, ive had several friends try to help and they aced alg-1 and the class this is coming from is agl-1 so yea, i dont know lol

Answer 5

Well that's odd lol

Answer 6

I've seen tons of things in the wrong classes (ex: trig in a geometry class...although they are related in a way). So I'm not surprised.

Answer 7

I'm assuming you want population standard deviations? or no?

Answer 8

all it says is standard deviation for a and b so yea sure lol

Answer 9

hmm ok, we'll deal with that aspect later

first we need to find the mean

Answer 10

what's the mean of class A?

Answer 11

72.7

Answer 12

close, but no

Answer 13

you add up the values in column A

then divide by 15 (there are 15 numbers in that column)

Answer 14

79?

Answer 15

good

Answer 16

calculator slip lol

Answer 17

now subtract the sample mean from every data value

Answer 18

make a separate column to the right of column A to represent the differences

Answer 19

I recommend using something like excel

Answer 20

sounds good lol gimme a sec

Answer 21

keep in mind you're only focusing on column A

Answer 22

ok

Answer 23

ok got it

Answer 24

1
6
8
13
7
11
15
21
-4
-34
6
-41
-7
15
-17

Answer 25

good

Answer 26

square every value in that list

make a new column of those squares to the right of that current column

Answer 27

ok
1
36
64
169
49
121
225
441
-16
-1156
36
-1681
-49
225
-289

Answer 28

each value in this column should be positive

example: (-17)^2 = +289 or just 289

this is in the last row, but there are other errors

Answer 29

ok, so ive changed them all to positives, but other errors?

Answer 30

no i meant the other negative values (as the other errors)

Answer 31

everything else looks good

Answer 32

oh lol ok

Answer 33

now add up the values in that last column

Answer 34

the column of squares

Answer 35

4558

Answer 36

off subject but what time is it where you are lol?

Answer 37

10:19 pm

Answer 38

now if we're finding the population variance, then we divide by n = 15

Answer 39

4558/15 = 303.8666667 roughly

Answer 40

that's the population variance

you take the square root of that to get the population standard deviation

Answer 41

soooooooo 92330.8996?

Answer 42

not squaring

square root

Answer 43

17.43

Answer 44

correct

Answer 45

you will do the same for column B

Answer 46

just with different numbers of course

Answer 47

good gracious lol

Answer 48

to summarize

step 1) find the mean
step 2) subtract the mean from each data value
step 3) square each data value
step 4) add up the squares
step 5) divide by N (number of values). this gets you the population variance
step 6) take the square root and you'll get the population standard deviation

Answer 49

you can use a formula but I don't recommend it unless you understand all of the symbols being used

Answer 50

ok thank you, lol its 1 in the morning where i am so im gonna finish in the morning lol thanks goodnight

Answer 51

sounds like a good plan, good night