Multiple choice general knowledge science & technology

A snail creeps 7 ft up a wall during the daytime. After all the labor it does throughout the day, it stops to rest a while... but falls asleep!! The next morning it wakes up and discovers that it has slipped down 5 ft while sleeping. If this happens every day, how many days will the snail take to reach the top of a wall 27 ft in height?

  1. 14

  2. 13

  3. 15

  4. 11
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Each day, snail makes net progress of 7-5 = 2 ft. After 10 days: reaches 20 ft (10 × 2). Day 11: climbs 7 ft from 20 ft → reaches 27 ft and stays at top (doesn't slip back once reached). Common mistake: calculating 27/2 = 13.5 and rounding to 14, but this ignores that on the final day, the snail doesn't slip back.

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