find an element in an array that is bigger than the mean, in constant time

function findFirstElementBiggerThanMean(array) {
  let mean = 0;
  
  for(let i = 0; i < array.length; i++) {
    mean += array[i]; 
  }
  
  mean = mean / array.length;
  
  for(let i = 0; i < array.length; i++) {
    if(array[i] > mean) {
      return array[i];
    }
  }
  
  return null;
}