Solve the simultaneous equations. You now know the probability of each value. Work out the standard deviation from the formula
(SD)^2=sum of (px^2)-(mean)^2.
Hey guys, I need help with this question:
The correct answer is 1.000, but I'm having trouble figuring out how to do itSuppose the random variable x = 1, 2, 3, 4, 5, 6. In addition suppose:
p(1)=p(2) and p(3)=p(4)=p(5)=p(6)
If the mean μ=4.00, then P(μ - 2σ ≤ x ≤ μ + 2σ) is:
from the question, i can derive two formulas
(1) 2a + 4b = 1
(2) 3a + 18b = 4.00
Formula (2) was derived from the expected value rule
not sure how to continue on from here... any help?
Let p1 = prob. x=1, p2= prob.x=2 and so on. We need the sum of px^2
That is p1(1)^2+p2(2)^2..........p6(6)^2 Then (sd)^2 =(sum of px^2)-(mean)^2. Perhaps you haven't seen this formula before but it is the correct one to use here.
Yes that's correct. So for the standard deviation subtract (mean)^2 (which is 16) and take square root. I get 1.528
In probability distributions of this kind learn the formulae
Mean = Sigma px and (SD)^2= sigma px^2-(mean)^2