help finding the variance- probibility?

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help finding the variance- probibility?

I know that the formula is E(X^2)-[E(X)]^2
But I seem ot be getting the wrong answer?
X= 1,2,2,4,5
Pr(X=x)= 0.35,0.3,0.1,0.2,0.05 (respectivly)
Find the variance.
Can you please show working out. Thanks

2006-10-04 23:30:51 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics

Sorry typo!
X=1,2,3,4,5

2006-10-04 23:31:25 · update #1

2 answers

E(x) = .35*1 + .3*2 + .1*3 + .2*4 + .05*5 = 2.3
E(x²) = .35*1 + .3*4 + .1*9 + .2*16 + .05*25 = 6.9
σ² = 6.9 - 2.3² = 6.9-5.29 = 1.61

2006-10-04 23:36:44 · answer #1 · answered by Pascal 7 · 0⤊ 0⤋

E= mc2

right?

2006-10-05 10:07:09 · answer #2 · answered by Made in Italy 4 · 0⤊ 0⤋