Snail's well
Algebra
Level
2
Suppose there's a snail at the bottom of a 10m well. Every day the snail climbs 3m - but during the night it slips down 2m. How many days will it take to scape the well?
The answer is 8.
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1 solution
On the first day, the snail climbs 3m and goes down 2m, so it stops 1m from the bottom of the well.
On the second day, we have: goes up 3m => 1 + 3 = 4m, but at the end of the day it slips 2m, hence 4 - 2 = 2m.
So the snail climbs 1m per day.
This goes on until the 7th day when the snail have climbed 7m.
On the 8th day, the snail climbs 3m, then we have 7 + 3 = 10m and, hence, it goes out of the well.