Question

i have a question, help me out..

The mean of four numbers is (p+2)^1/2. the sum of the squares of the numbers is 64 and the standard deviation is 2m.

express p in terms of m

Answer 1

know the formula for std deviation ?

Answer 2

no

Answer 3

\(\Large \sigma = \sqrt{\frac{1}{N} \sum \limits _{i=1}^N (x_i - \mu)^2}, {\rm \ \ where\ \ } \mu =Mean = \frac{1}{N} \sum \limits_{i=1}^N x_i.\)

Answer 4

ever seen that ?

Answer 5

oh yes

Answer 6

and then what?

Answer 7

ok, so sigma = 2m
N=4
x1 to x4 are our 4 numbers

Answer 8

ok....

Answer 9

from mean , we have
x1+x2+x3+x4 = (p+2)^1/2
and x1^2+x2^2+x3^2+x4^2 =64 is given

Answer 10

oh ok...

Answer 11

nah, i made an error,
(x1+x2+x3+x4)/4 = (p+2)^1/2

Answer 12

let me check whether there's an easier alternate way to do this...

Answer 13

hurm... i get p = 14 - 4m^2

is it correct

Answer 14

what the easier alternate way to do this...

Answer 15

how did you get that answer ?

Answer 16

and yes i too get 4m^2 =14 -p

Answer 17

which gives me p as 14 - 4m^2

Answer 18

i did it the long way which i showed you

Answer 19

how

Answer 20

4m^2 =(1/4)[ (x1^2+x2^2+x^2+x4^2) -2 mu * (x1+x2+x3+x4) +4mu^2 )]
if you plug in values and simplify, you'll easily get that

Answer 21

oh, same as mine

Answer 22

:)

Answer 23

thanks

Answer 24

welcome ^_^