text: const CustomError = require("../extensions/custom-error");
  
  const MODERN_ACTIVITY = 15;
  const HALF_LIFE_PERIOD = 5730;
  
  module.exports = function dateSample(sampleActivity) {
    if (typeof sampleActivity !== 'string' || Math.sign(sampleActivity) !== 1 || +sampleActivity > 15) {
      return false;
    }
  
    return Math.ceil(-HALF_LIFE_PERIOD * Math.log(+sampleActivity / MODERN_ACTIVITY) / 0.693);
  };
  