|
안녕하세요!
L24에서 practice question E241 (b)에 관해서 질문이 있는데요
이게 standard deviation of X를 구하는 것인데 X=A+B이기 때문에 linear combination이잖아요.
근데 linear combination에서 공식을 보면 variance가 제곱이 되는 것이잖아요.
σz^2= σx^2 + σy^2 이렇게요.
그럼 although the question asks for standard deviation, since it's a linear combination in which we have to find standard deviation through the sum of variances,
don't we have to find it though
σx^2 = σA^2 + σB^2 ??
in the lecture, 풀이과정 보면 σx= σA + σB 라고 되어있어서 질문합니다!!
Thanks!
==================================
You are right, this is a mistake.
the answer should be sqrt(40^2+48^2) = 62.48..
I looked through the lecture;
I can't remember what I was thinking at the time.. presumably I was thinking of variances.. or donuts...
Thank you for pointing this out! I will correct this in a future recording.
|
