Question

Algebra 2 help please

Answer 1

Mrs. Jones Algebra 2 class scored very well on yesterday’s quiz. With one exception, everyone received an A. Within how many standard deviations of the mean do all the quiz grades fall?

91, 92, 94, 88, 96, 99, 91, 93, 94, 97, 95, 97
(1 point)

2
1
3
4

Answer 2

calculate the mean first

Answer 3

93.9 = 94

Answer 4

now minus it from each value and square it

Answer 5

like (91-94)^2 = (-3)^2 =9

Answer 6

so i do that for all of them?

Answer 7

yes for all

Answer 8

and calculate their mean
that's your standard deviation

Answer 9

9,4,0,36,4,25,9,1,0,9,1,9

Answer 10

98.7=99

Answer 11

shouldn't it be 8?

Answer 12

what do you mean?

Answer 13

9,4,0,36,4,25,9,1,0,9,1,9
calculate mean of these

Answer 14

i did and i got 98.7=99

Answer 15

add them
and divide by 12
@electrokid how do you find how many standard deviations are there

Answer 16

and square-root

Answer 17

sd dev = sqrt of ( mean of ( squares of difference of each value from its mean

Answer 18

oh yeah
sorry

Answer 19

and how to find the number of standard deviations? @electrokid

Answer 20

@aajugdar what do you mean number of std dev?

Answer 21

im so confused

Answer 22

Within how many standard deviations of the mean do all the quiz grades fall?

Answer 23

@vivianrush you did correct... looks like all that is left is a square-root

Answer 24

@aajugdar oh. k max sample value / std dev

Answer 25

and round it up

Answer 26

@vivianrush
\[\sqrt{(9+4+0+36+4+25+9+1+0+9+1+9)/12}\]

Answer 27

oh

Answer 28

0.86

Answer 29

~_~ its not 0.86

Answer 30

its 8.91 take it as 9 take root of it
ans =3

Answer 31

so @electrokid 99/3 = 33
what after this

Answer 32

yes a little more than 3.
and the ans = max diff from mean / std dev

Answer 33

no..
the question asks for
$$\sigma_{mean}=\frac{\sigma}{\sqrt{N}}$$
sigma = what you found above
N = 12

Answer 34

so its 3/sqrt12

Answer 35

its less than 1 :/

Answer 36

ok,almost 1 considering SD is more than 3

Answer 37

mean / std dev

Answer 38

yes that should be it

Answer 39

so answer will be 1

Answer 40

im still confused,but thank you guys

Answer 41

@vivianrush @aajugdar (99-93.9)/3.1 = 5.1/3.1 = 2 (within two standard deviations from mean)

Answer 42

haha xD
@vivianrush calculate mean of samples
then minus it from samples and square
then you got these 9,4,0,36,4,25,9,1,0,9,1,9
now calculate their mean and calculate its root
you will get standard deviation
and then use the formula that electro gave

Answer 43

oh i see