Answer:
Number of days needed = 57
Step-by-step explanation:
Depth of well = 115 feet
Distance traveled in day = 3 feet up
Distance traveled in night = 1 feet down.
Total displacement in 1 day = 3 - 1 = 2 feet up
When the snail reaches 112 feet up, the next 3 feet up motion on day will make it reach the top.
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After 56 days the displacement of snail is 112 feet.
On the next day it moves up by 3 feet and reaches out of well.
Number of days needed = 57