VaR- Value at Risk

Hi @Admin & Group members,

I was learning the VaR concept yesterday and the VaR did not sink in quiet well! 🙁
I do not have a statistic background, but i would really appreciate it if someone explained to me why we have to multiply the nth year to the weight of the discounted return to come up with the payback period for HALF of the total returns… ie

1- 10,000
2- 15.000
3- 20,000
4- 15,000
Total- 60,000/-
Y1 (10,000/60,000)*1=1.667
Y2 (15,000/60,000)*2=0.5
Y3 (20,000/60,000)*3=1
Y4 (15,000/60,000)*4=1
Total = 4.167 years… (my concern area is the *1 *2 *3 and *4)

Thanks & Regards,