JS-If-a-random-variable-X-follows-normal-distribution-with-mean-30-and-variance-25-What-is-the-probalility-of-X-is-less-than-28-

Question Number 108334 by john santu last updated on 16/Aug/20

\frac{⊸ J S ⊸}{△}

I f a r a n d o m v a r i a b l e X f o l l o w s n o r m a l

d i s t r i b u t i o n w i t h m e a n 30 a n d

v a r i a n c e 25 . W h a t i s t h e p r o b a l i l i t y

o f X i s l e s s t h a n 28 ?

Answered by bemath last updated on 17/Aug/20

\frac{△ B e M a t h △}{△}

X \sim N (30, 25)

P (X < 28) ?

z = \frac{x - μ}{σ} = \frac{28 - 30}{\sqrt{25}} = - \frac{2}{5} = - 0.4

P (X < 28) = P (z < - 0.4)

= 1 - P (z ⩽ 0.4)

= 1 - 0.6554

= 0.3446

Facebook Tweet Pin