A bag of balls in code

You will work out probabilities for a bag of coloured balls, find how many balls to add, and test the theory by drawing many times.

Your tasks.

1. In p_colour, return the probability of drawing colour from bag as a Fraction. The bag is a dictionary such as {"red": 3, "blue": 5}.
2. In red_to_add, return the smallest number of red balls to add so that the probability of red is at least target.
3. Draw one ball $6000$ times from the bag {"red": 2, "blue": 3, "green": 5}, putting it back each time, and set share to the fraction of draws that were red.