A Man, Shipwrecked at Sea, Spends 12 Hours Floating in the Ocean

Essay

A man, shipwrecked at sea, spends 12 hours floating in the ocean before washing up on the shore of a deserted island. By the time he reaches the island, he is severely dehydrated. He has several options for correcting his water balance: Assume that under normal conditions, his blood has 0.01 grams of salt per 1,000 grams of water, but under severe dehydration, the salt content increases to 0.5 grams per 1,000 grams of water.
• He could drink ocean water, which contains 37 grams of salt per 1,000 grams of water.
• He could drink from a puddle of rainwater that has been somewhat contaminated by sea water, but is not as salty as pure sea water and contains about 7 grams of salt per 1,000 grams of water.
• He could eat berries that contain 0.006 grams of salt per 1,000 grams of water, but the berries have been coated in salt spray that covers the outside of the berries with salt. For each 100 grams of berries, they are covered in 5.5 grams of salt.
• He could catch raindrops in his mouth when storms pass. He could manage to catch 10 drops per minute, and one milliliter of water contains 20 drops of water. However, he would also lose 300 milliliters of water per hour through respiration.
Which of the scenarios would provide him with the least amount of salt and the highest percentage of water most quickly? He can only use these options, but must come up with a creative solution to maximize his survival chances. What is his best course of action?