Combination doubt

Question

A shipping clerk has to weigh 10 distinct packets. He weighs them four at a time, weighing all the possible combinations of the packets from the ten. The average weight of all the weighing combination is found to be 800 gm. What is the combined weight of all the size packets?

Answer 1

Average weight of 4 packets = 800 gm

So, each packet weights--> 800/4 =200 gm

So 10 packets weight--> 200*10 =2000 gm