What is to be done when determing z-values and probabity when the given value doesnt have a clean answer. For example: What is the value of z for a probability of 0.700. The table gives z
of 0.524 to be 0.699. Should I go up to 0.525 (which gives 0.7002)
or stay at 0.524.
Also 0.9981 has a range of z from 2.90 to 2.99. What value should be
The book I am using says just obtain Fi(z)= p by
interpolating. Nothing fancy though. Yet I'm having lots of problems
like the ones below.
The random variable Z~N(0,1). Find the value of u.
P(Z>u) = 0.0071 As the table only gives positive z values, this
P(Z<=u) = 0.9929. The book says to look for a value of z for Fi(z)
=0.9929. However the value that it gives is 2.452 even though 2.450
also gives the same answer. To me this makes sense as you want the
highest value that gives the required probability. But the book says
nothing about this. It just says to find the value of Fi(z)= p and
to intepolate if the value of p is between to values of z.
P(Z>u)=0.9977. The range of values of Fi(z) is -2.847 to -2.828 and
the answer given is -2.834. Why?
Thanks a lot.