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Hi I am trying to create a function that will calculate the mean of a column in a dataframe, without using python built in functions.

This is how I did it initially

```
A B
0 180.0 70
1 170.0 65
2 190.5 80
3 175.0 75
4 190.0 90
5 190.0 90
6 195.0 95
7 200.0 100
8 205.0 105
9 210.0 110
```

```
n =len(df2["B"])
total = sum(df2["B"])
mean=total/n
```

Now I wanted to create a built in function this was my attempt but it is giving me an error. Please assist where I went wrong. (A disclaimer this is a tutorial question).

```
def summary_statistics(df, column_name):
n =len(df2[column_name])
total=sum(df2[column_name])
mean = total/n
return mean
summary_statistics(df2,["B"])
```

### >Solution :

You need to do this:

```
def summary_statistics(df, column_name):
n =len(df[column_name])
total=sum(df[column_name])
mean = total/n
return mean
summary_statistics(df2, "B")
```