how do I find the answer to P(z<-1.26)

Question

I can't seem to figure out how to calculate the answer to this question. I have a few more that I can't seem to get either:

 

P(Z < -1.26)

 

P(Z > 0.72)

 

P(-1.52 < Z < 2.66)

 

Answer 1

 

Hi Michael,

 

You actually need to look up the table for the standard normal distribution.

 

Just google "standard normal distribution table", and

 

if you find one,

 

read the probability value corresponding to the Z value.

 

Depending on the way they represent,

 

the probability may represent the area to the left or right of the Z value.

 

Refering to the table in which the probability represents the area to the left of the Z value,

 

     P(Z < -1.26) = 0.1038

 

     P(Z > 0.72) = 1 - P(Z < 0.72)

                       = 1 - 0.7642

                       = 0.2358

 

     P(-1.52 < Z < 2.66)

                       = P(Z < 2.66) - P(Z < -1.52)

                       = 0.9961 - 0.0643

                       = 0.9318

 

Hope this helps.