## 3rd and 4th Grade, February, 2020

A.1289. The emperor penguin takes half of its water needs from snow, and the other half from seawater. These penguins can drink salt water because their supraorbital (just above the eye) gland filters excess salt from their blood stream. They can make 6 dL of fresh water from 2 L of salt water. How many liters of seawater will an emperor penguin clean in a month, if it needs 9 L of fresh water in that time?

A.1290. A colony of penguins are marching to the sea. Whether they march in groups of 2, or 3, or, 4 or 5, one penguin will always be left alone at the end of the groups. How many penguins are there in this colony if the number of penguins in it is between 950 and 1000?

A.1291. Some penguins are able to dive to a great depth while hunting for crabs. They can swim with a speed of 90 meters per minute. How far can they get from their nests in a day if they rest only for 4 hours?

A.1292. The endangered, flightless takahe is a colorful green and blue bird that is only found in New Zealand’s high mountains. The number of these birds rounded to one of the place values is 1100. If there were 3 less of these birds, and you rounded their number to the same place value, you would get 1000. What is the highest possible number of takahes in the world?

A.1293. The kakapo (night parrot), also called owl parrot, can also be found only in New Zealand. The kakapo does not breed every year and has one of the lowest rates of reproduction among birds. There were only 81 of them last year, making it a critically endangered bird. One fifth of its males is the same number as one fourth of its females. How many male and how many female kakapos live on the Earth?

A.1294. Groundhogs are well adapted for digging, with short but powerful limbs and curved, thick claws. The average groundhog has been estimated to move approximately 1 m3 or 320 kg of dirt when digging a burrow. Groundhog burrows usually have two to five entrances, providing groundhogs their primary means of escape from predators. In the following tunnel system, how many different ways can a groundhog get from burrow A through burrow D to burrow E, if it cannot use any tunnel and any burrow more than once? (Two ways are different if the order of the burrows is different or the tunnel used between any two burrows is different.) Which one of these ways is the shortest?

A.1295. The Giant Armadillo is an interesting mammal that lives in the rainforests of South America. One third of its length is accounted for by the tail, and one fourth of the rest of its body-length is its head. How long is a Giant Armadillo with a head size of 18 cm?

A.1296. The saltwater crocodile is the world’s largest living reptile in terms of mass. Adult males can reach sizes of up to 6 meters and 1000 kg. Researchers measured the masses of 4 baby crocodiles (Badu, Kitoko, Davu and Iniko), one-by-one. The heaviest crocodile is 47 dkg, and the lightest crocodile is 23 dkg, but there is a 36-dkg crocodile amongst them, also. Badu is not the heaviest crocodile, but he is heavier than Kitoko. Davu is lighter than Iniko. Only Kitoko is lighter than Davu. The four of them together have a mass of 1 kg 36 dkg. What is the mass of each baby crocodile? (1 kg = 100 dkg)