Difficulty: Medium

A snail is trying to climb a 10-meter poll. Every day it climbs 4 meters up and then during the night slides 3 meters down. How many days are needed for the snail to get to the top of the poll?

Seven days only. After the sixth day, the snail would have climbed 6 meters. During the seventh day, it will climb 4 more meters and will get to the top.

Two people – Mick and Goof, 100 meters apart, start walking towards each other with constant speeds of 2m/s. At the same time Mick’s dog starts running back and fourth between them with constant speed of 6m/s until Mick and Goof meet. How much distance does the dog cover in total?

Mick and Goof will meet after 100/(2 + 2) = 25 seconds. Therefore the dog will run for 25 seconds and will cover 6 x 25 = 150 meters in total.