TIMO Khối 9 – Vòng Quốc gia (Heat Round) – Đề số 1

Selena's dessert is stolen, she asked her 4 guests and received replies: Hera: "David's stolen it." David: "Steve's stolen it." Ruby: "I have not stolen it." Steve: "David is lying." Given that only one of them had told lies, who stole Selena's dessert?

Lying: Nói dối; Told the truth: Nói thật.

If x, y and z are all prime numbers and y x x y z + = , find the value of z.

Prime: Số nguyên tố

Divide a rectangle into 3 6  identical small squares and paint each small square in either red or green. How many ways to paint them so that there doesn't exist a rectangle with area not less than four with four cells at four corners are painted in same color?

Rectangle: Hình chữ nhật; Identical small squares: Hình vuông nhỏ y hệt nhau; Area: Diện tích;

Cells: Ô; Corners: Góc.