1 - mother had five sons, each of them had a sister. How many children has a mother?
2 - Three people jumping with a parachute, the first person weighs 70kg, 80kg second, while the third 100kg. What kind of people were the first on earth?
3 - Ladder hanging on the side of the ship anchored in the harbor. The lowest rung of the ladder touches the water, and the distance between rungs is 20cm, and the length of the ladder is 180cm. The height of the water increases at a rate of 15 cm per hour. When the water reaches the height from the top of the seventh rung?