From a sample to the whole school

You will write three small functions that turn a sample into numbers about the population: the sample percentage, an estimate of a total, and the spread of several statistics.

The idea. A sample is stored as a list of 1s and 0s: 1 for a student who has the property, 0 for one who does not. The sample percentage is $\hat p = \dfrac{\text{number of 1s}}{n} \times 100$. If a fair sample is used for a population of $N$, the estimate of the total is $N \times \dfrac{\text{number of 1s}}{n}$.

Your tasks.

1. Finish share(sample). Return the percentage of 1s in the list.
2. Finish estimate_total(sample, N). Return the estimated number in a population of N.
3. Finish spread(statistics). Return the largest value minus the smallest value.