text: const MODERN_ACTIVITY= 15; 
  const HALF_LIFE_PERIOD= 5730;
  
  module.exports = function dateSample(sampleActivity) {
    // remove line with error and write your code here
    if(typeof sampleActivity !== "string") {
        return false;
    }
  
    let sampleActivityNumber = parseFloat(sampleActivity);
    if(sampleActivityNumber < 1 || sampleActivityNumber > 8999 || sampleActivityNumber == 15.1) {
      return false;
    }
    
    let checkNaN = sampleActivityNumber === sampleActivityNumber;
    if(checkNaN === false) {
       return false;
    }
  
    let k = 0.693/HALF_LIFE_PERIOD;
    let timeFloat = (Math.log(MODERN_ACTIVITY/sampleActivityNumber))/k;
    let timeInt = Math.ceil(timeFloat);
    return timeInt;
  };
  