Question

What is area under the normal curve between `z=-2.0` and `z=-1.0`?

Answer 1

Area under the normal curve between `z=-2.0` and `z=-1.0` is `0.1359`.

Explanation:

To find area under the normal curve between two values of `z`, we can use tables.

However, tables give areas from `z=0` to `z=3.9` (beyond which there is literally no change). But as normal curve is symmetric at `z=0`, we can use it to find are between any two given `z` values.

For example for area unde the curve between `z=-2.0` and `z=-1.0` we can take values for `z=2.0` and `z=1.0` and their difference will give area between `z=-2.0` and `z=-1.0`.

From tables for `z=1.0`, we have `0.8413` and for `z=2.0`, we have `0.9772` and hence

Area unde the curve between `z=-2.0` and `z=-1.0` is `0.9772-0.8413=0.1359`.