Radioactive Decay

A half life is the amount of time for half of a radioactive substance to decay.

• After 1 half life, 50% of a substance will be left.
• After 2 half lives, 25% of a substance will be left.
• After 3 half lives, 12.5% of a substance will be left, etc...

Create a function which calculates the remaining mass and the number of years that it took for the substance to decay. You will be given:

• The mass of the substance.
• The time in years for a halflife to elapse.
• The number of half lives.

Worked Example

halflife_calculator(1000, 5730, 2) ➞ [250, 11460]

# There are 2 half lives, so the mass decays from 1000 to 500, then from 500 to 250.
# Each halflife is 5730 years, and since there were 2, it took 11460 years in total.

Examples

halflife_calculator(1600, 6, 3) ➞ [200, 18]

halflife_calculator(13, 500, 1) ➞ [6.5, 500]

halflife_calculator(100, 35, 5) ➞ [3.125, 175]

Notes

• Round the final mass to three decimal places.
• All inputs are positive numbers.
• Return the final mass first, then the number of years.