In the movie Aliens, how long was Newt alone on the Hadley's Hope colony? The only information we are given is during an exchange that Hudson and Ripley have. Someone mentions that a search party won't be sent out for 17 days. Hudson then says that he doesn't want to be there for 17 more hours let alone days. Ripley follows up by saying Newt survived longer than that with "no food and no training".
So how long was Newt actually alone?
In the ‘Aliens’ novel Hicks and Hudson mention at various points that the trip between Earth and LV-426 takes 3 weeks. Hicks also mentions that the earliest rescue would be expected after 17 days (nearly 3 weeks). Possibly a rescue ship would be faster than a troop transport, or the rescue ship could be stationed a bit closer to LV-426.
So we can assume from loss of signal to arrival of Marines was about three weeks. In which case Newt DID survive that long "without weapons of any kind," to quote Ripley.
See FTL in the Alien franchise for further information on the speed of FTL ships in the Aliens universe.
They lost contact with the colony, we can assume that is likely to be just before the last stand. Although we have no way of knowing when exactly Newt became separated from everyone else.
Say approximately a day before they realised comms were properly down and not a glitch (as Burke knew what was happening).
Another day (at least) to speak to the company and be granted use of a marine squad.
Visit Ripley, get rebuffed.
It was at least a day until Ripley reconsidered the request to accompany the troops.
At least another day to prepare
The trip takes 3 weeks.
Therefore it would be at least 25 days.
You guys forgot to add the time to call Earth from LV-426. In the extended version they talk about that it takes 2 weeks to send a message (or a week to send and another week to get answer, I don't remember exactly). So in the best case scenario, when the settlers sent their last message on the day they all got attacked will add 1 or 2 weeks to 3 weeks Newt spent alone.
