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Let’s see how the grades varied against the average. This is called computing the variance.

A very large variance means that the students’ 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)`.

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