I'll give you an example. Try to work your questions and post what you did before asking a question next time.
Qu. The heights of female students at a particular college are normally distributed with a mean of 169 cm and a standard deviation of 9 cm.
(a) Given that 80% of these female students have a height less than h cm, find the value of h.
(b) Given that 60% of these female students have a height greater than s cm, find the value of s.
Solution:
Let X represent the height, in centimetres, of a female student.
(a) Given
Standardising;
Let
The corresponding z value in your table for this probability is 0.842
Hence,
So,
(b) Given
Standardising;
Let
But if you made a sketch of the normal table and shaded the right area, you'll see that z must be negative.
This z value corresponding to the probability is given by -0.253 in your table.
Hence
So,
Questions? :)