Many years ago, a cruise liner sank in the middle of the Pacific Ocean.
The survivors luckily landed on a remote desert island.
There was enough food for the 220 people to last three weeks.
Six days later a rescue ship appeared, unluckily this ship also sank, leaving an additional 55 people stranded on the island to now share the original rationed food.
The food obviously had to be re-rationed, but everyone was now on one-half of the original ration, so how many days in total would the food last for, from the day of the original sinking?
Answer: 30 days.
Originally there was enough food for 220 people for 21 days, which totals 4620 rations.
After 6 days 1320 rations were eaten.
Therefore there were now 3300 rations for 275 people, which would last for another 24 days at one-half ration per person.
Which is 30 days in total from the original sinking.