Standard Deviation Calculator

calcStandardDeviation.js

function calcStandardDeviation(arr) {
  // var arr = [23, 37, 45, 49, 56, 63, 63, 70, 72, 82];
  var count = arr.length

  var mean = arr.reduce(function(total, num) {
    total += num;
    return total;
  }, 0) / count;

  var variance = arr.reduce(function(total, num) {
    var diff = num - mean;
    total += diff * diff;
    return total;
  }, 0) / count;

  var sd = Math.sqrt(variance);

  return sd;
}