Question

An intelligence test used in a particular country has scores which are normally distributed with mean 100 and standard deviation 15.In a randomly selected group of 500 people sitting the test, estimate how many have a score
i.higher than 140
ii.between 85 and 90

Answer 1

In my days, we had to calculate stuff like "z-scores" and look at tables in the back of text books.
Now-a-days, there are webpages like
http://davidmlane.com/normal.html

that makes these type of questions almost trivial.

Answer 2

An intelligence test used in a particular country has scores which are normally distributed with mean 100 and standard deviation 15.In a randomly selected group of 500 people sitting the test, estimate how many have a score
i.higher than 140
ii.between 85 and 90