1 | initial version |

Two issues here:

1) Sage is trying to evaluate the sum command as if it is a Python expression. So, to turn it into a function, you can do:

```
f=lambda x: add([.25^(100-i) * .75^(i) * binomial(100,i) for i in range(0, x)])
```

2) The plot command tries to plot at non-integer points, so your command will not plot. You can try the following:

```
pts=[point([x,f(x)]) for x in range(1,101)]
p=add(pts)
show(p)
```

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