Letâ€™s see how the grades varied against the average. This is called computing the *variance*.

A very large variance means that the studentsâ€™ grades were all over the place, while a small variance (relatively close to the average) means that the majority of the students had similar grades.

### Instructions

**1.**

On line 18, define a new function called `grades_variance`

that accepts one argument, `scores`

, a list.

First, create a variable `average`

and store the result of calling `grades_average(scores)`

.

Next, create another variable `variance`

and set it to zero. We will use this as a rolling sum.

`for`

each `score in scores:`

Compute its squared difference: `(average - score) ** 2`

and add that to `variance`

.

Divide the total `variance`

by the number of `scores`

.

Then, return that result.

Finally, after your function code, `print grades_variance(grades)`

.