Rates from a table of readings

You will write functions that turn a table of concentrations into rates. One finds the average rate in each interval. One picks the fastest interval. One finds the rate of the reaction from the rate of change of a single substance.

The idea. The average rate in an interval is $\dfrac{-\Delta[\text{R}]}{\Delta t}$. The rate of the reaction is the rate of change of a substance divided by its coefficient.

Your tasks.

1. Complete average_rates(times, conc) so that it returns a list with the average rate for each interval between neighbouring readings, as positive numbers.
2. Complete fastest(rates) so that it returns the number of the interval with the highest rate, counting from 1.
3. Complete reaction_rate(rate_of_change, coefficient) so that it returns the rate of the reaction as a positive number.