3rd and 4th Grade, January, 2020

    A.1281. Odett drew into a square all of its axes of symmetry. A total of how many triangles and quadrilaterals are there on the picture?

    A.1282. Find all those 2-digit numbers in which the sum of the digits is odd, and it (the sum of the digits) remains odd even if you add one to the number.

    A.1283. How many 3-digit numbers do not contain the digit 5?

    A.1284. There are red, blue, and yellow cubes in a black bag. You have to take out 15 of them randomly in order to have a yellow in your hands for sure, you have to take out 17 of them randomly in order to have a red in your hands for sure, and you have to take out 19 of them randomly in order to have a blue in your hands for sure. How many cubes of each color are there in the bag?

    A.1285. On the diagram each arrow points towards the taller penguin. One of the penguins is 92 cm tall. There is a taller by 16 cm and two shorter penguins, one of them by 37 cm and the other by 54 cm shorter. How tall is each penguin?


    A.1286. The King Penguin feeds its big baby every third day. Each time she gives her baby about 3 kg of calamari. Each calamari has a mass between 150 grams and 200 grams. Hunting for food, the King Penguin dives 860 times a day, and only a tenth of them are successful.

    a) At least how many calamaris does the mama penguin have to catch if she wants to feed her baby for 3 weeks?

    b) During the 3 weeks, how many times does the mama penguin dive unsuccessfully?

    A.1287. The number of penguins in this colony is the greatest even number which when rounded to the nearest hundreds is 1300, and if you round it to the nearest tens then the sum if its digits is 9. How many penguins live in this colony?

    A.1288. Five baby penguins eat as much as two adult penguins. How much fish do five adult penguins eat in a week, if 8 babies eat 320 dkg of fish daily? (100 dkg = 1 kg)

    Please send your solutions here.

    The Sharma Kamala Educational Trust is sponsoring the participation of students from India. So, if you are a student living in India, please, send your solutions to: Group A from India

    Back to Paul Erdős International Math Challenge

    Posted in Uncategorized | Comments Off on 3rd and 4th Grade, January, 2020