Assuming the Standard Normal Distribution, find:

Question

Assuming the Standard Normal Distribution, find:

a. 15% of the cumulative probability is above what value for Z? Is it 1.04 or 1.036


b. Between what two values of Z (symmetrically distributed around the mean) will be80% of all possible values of Z be contained? really dont know where to start

Answer 1

THe probability z < 1.04 is -1.036 per the normal table.

 

You said the CUMULATIVE probability, which is another table.

The probability accumulates to 15% around 0.385 which is the

area under the normal curve from 0 to x=0.385

 

Here's a link to the table: http://www.itl.nist.gov/div898/handbook/eda/section3/eda3671.htm

 

-1.285 < x < 1.285 will give you 80% of the probability symmetrically distributed about the mean of zero

per reading the normal table in reverse. Specifically you are looking for z where the probability is 0.1 and 0.9