What three factors led up to the deaths of Hal, Charles, Mercedes and the dog sled team in Chapter 5 of Call of the Wild?

These three "chechaquos" learned about the terrible
hardships of the Yukon the hard way. Although they were anxious to find the riches of
gold, they were not willing to learn the rules of survival that faced them on their
journey. Everything Buck saw about them was in "disorder," from the dirty dishes to the
"slipshod" manner that they set their tent. The group was totally out-of-place in the
harsh environment, and they made many mistakes along the way. Perhaps their biggest
mistakes were:

• Overloading their sled with
  unnecessary items, such as canned goods, excessive clothing, and personal items. The
  woman, Mercedes, refused to walk, so she further weighed down the sled by riding on
  it.


• Using fourteen dogs, an excessive number, in part
  because enough food could not be carried.


• Spending too
  much time in camp and not leaving early enough each
  morning.


• Overfeeding the dogs, which caused them to run
  out of food even sooner.


• Not heeding the good advice that
  they would arrive at the White River too late, and that they would not be able to travel
  over the thin ice.