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1965 Leningrad Math Olympiad - Grade 7

Source:

August 30, 2024
leningrad math olympiadalgebrageometrycombinatoricsnumber theory

Problem Statement

7.1 Prove that a natural number with an odd number of divisors is a perfect square.
7.2 In a triangle ABCABC with area SS, medians AKAK and BEBE are drawn, intersecting at the point OO. Find the area of the quadrilateral CKOECKOE. https://cdn.artofproblemsolving.com/attachments/0/f/9cd32bef4f4459dc2f8f736f7cc9ca07e57d05.png
7.3 . The front tires of a car wear out after 25,00025,000 kilometers, and the rear tires after 15,00015,000 kilometers. When you need to swap tires so that the car can travel the longest possible distance with the same tires?
7.4 A 24×6024 \times 60 rectangle is divided by lines parallel to it sides, into unit squares. How many parts will this rectangle be divided into if you also draw a diagonal in it?
7.5 / 8.4 Let [A] [A] denote the largest integer not greater than AA. Solve the equation: [(5+6x)/8]=(15x7)/5[(5 + 6x)/8] = (15x-7)/5 .
7.6 Black paint was sprayed onto a white surface. Prove that there are two points of the same color, the distance between which is 19651965 meters.
PS. You should use hide for answers.Collected [url=https://artofproblemsolving.com/community/c3988081_1965_leningrad_math_olympiad]here.