A snail creeps 10 feet up a wall during the daytime, then falls asleep. It wakes up the next morning and discovers it slipped down 6 feet. If this happens each day, how many days will it take to reach the top of a 20 foot wall?
Four days.
Day 1: up to 10, down to 4
Day 2: up to 14, down to 8
Day 3: up to 18, down to 12
Day 4: up to 22 (20 really) and done
7 Comments on "Snail Up The Wall"
Pavan suresh says
June 27, 2015 @ 01:09
Its 5 days and not 4 days!!
Dan says
June 30, 2015 @ 21:27
Nope, it’s 4. Draw a diagram for each day and you’ll see why.
Jordan says
July 5, 2015 @ 18:49
Awesome
Lisa says
March 29, 2016 @ 07:28
It’s 4 days. It seems like it should be 5 days, but at the end of day 4, snail will be at the top of the wall, so he won’t slip back 6 feet like every other day.
Ed says
April 13, 2017 @ 01:11
what feirce determination
Palash says
August 2, 2019 @ 06:13
its 4 days.
after 3 days it will rise up to 12 feet. and then next day it will able to rise 10 feet before it will fall asleep. so it will already rise up the wall before day four ends
Arijeet says
August 7, 2019 @ 20:53
It’s 4 days
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