JSFiddle - React, Tailwind, and code Playground

HTML

<div class="response"></div>

TypeScript

function minutesToHour (minutes) {
	let resultMinutes = Math.ceil(minutes % 60);
  let time = Math.floor(minutes / 60) + ':';
  time += resultMinutes < 10 ? '0' + resultMinutes : resultMinutes;
	return time;
}

function hourToMinutes (hour) {
	let hAndM = hour.split(':');
  let h = parseInt(hAndM[0]);
  let m = parseInt(hAndM[1]);
  return h * 60 + m;
}

function getTimeAverage (timeArr: any) {
	let allTime = 0;
  for (let time of timeArr) {
  	allTime += hourToMinutes(time)
  }
  return minutesToHour(allTime / timeArr.length);
}

const t1 = '16:51'
const t2 = '17:04'

document.querySelector('.response').innerHTML = getTimeAverage([t1, t2])


function getTimeAmount (timeArr: any) {
  let allTime = 0;
  
  for (let time of timeArr) {
  	allTime += hourToMinutes(time)
  }
  
  return minutesToHour(allTime);
}
document.querySelector('.response').innerHTML += '<br>' + getTimeAmount([ '06:10', '06:10', '06:50' ]);