The questions are about Gaussian random variables. I have DC supply voltage represented by a random variable Y. The voltage should not be much higher than the intended operating voltage for any extended period of time.
DC supply variance is 0.1 V^2 when operating at 10 V
a) What is P[X>10.65] b)The supply is connected to two resistances, R1 = 10Ogm and R2 = 40 Ohm, they are connected in series. What is the variance of voltage across R2?
Concerning a) I use Z = (X - mu)/sigma = 1.732 P[Z>1.732] = 0.0418 - The book says that the answer should be 0.02 Concerning b) I do this Var(V2) = R2^2 * Var(Y) / (R1 + R2)^2 and get answer 0.007 while answer should be 0.006
What am I doing wrong?