Could someone explain the last line of this solution? I do not understand how th
ID: 3325725 • Letter: C
Question
Could someone explain the last line of this solution? I do not understand how the when using the standard normal distribution, P(P>0) = (-1.68) = 2(1.68) -1. I thought that P(X>x) = 1-P(X<x) = 1- (-1.68) = (1.68) and that the 2 (-1.68)-1 only comes about when we're looking for the probability that P is between two values.
Problem #1 (17 points) -A Positive Product Suppose that X and Y are random variables with expected values E(X) = 12 and E(Y) - 12 and covariance matrix Cov(X. X) Cov(X,Y)143 -5 OV OV If the product P = XY is modeled as a normal distribution, compute the probability that P is positive.Explanation / Answer
You are right. I also think the calculation done in the formula is wrong.
The right calculation is simple: P(Z>-1.68) = 1- P(Z<=-1.68) = 1- .0465 = .9535 ( I used the Z tables for this)
Why is there need to find the answer this way when you have a Z value of 1 side. The way calculation has been done is when 2 Zs are given and you have to find values between the two Zs
The answer of .907 is actually when you try to find out P(Z< |1.68|)