TIMO Khối 9 – Vòng Quốc gia (Heat Round) – Đề số 4

There are 21 problems in a mathematics competition. The scores of each problem are allocated in the following ways: 2 marks will be given for a correct answer, 1 mark will be deducted from a wrong answer and 0 marks will be given for a blank answer. Find the minimum number of candidate(s) to ensure that 5 candidates will have the same scores in the competition.

Allocated: Được quy định; Deducted: Bị trừ; Minimum number of candidates: Số thí sinh ít nhất;

Same scores: Số điểm bằng nhau

If 26664 abcd bcda cdab dabc + + + = , calculate a b c d + + + .

Calculate: Tính

There are 53 pieces of white chopsticks, 21 pieces of yellow chopsticks and 41 pieces of brown chopsticks mixed together. Close your eyes. If you want to get 2 pairs of chopsticks that is not white colour and 2 pairs of chopsticks that is not yellow colour, at least how many piece(s) of chopstick(s) is / are needed to be taken?

Pairs of chopsticks: Đôi đũa; At least: Ít nhất.