At a conference, one quarter of the participants occupy two thirds of the chairs. The other participants stand. If 3 chairs are empty, how many people are standing?
Vinh arranges fish and bird pictures in a table with 6 rows and 22 columns as shown, with one third as many birds as fish. How many fish pictures are there?
In a city, 94% of children in the age group due for measles vaccination have been vaccinated. If 24 children in this age group have not been vaccinated, how many children are in the age group?
On 15/03/2016, Vu notices that the sum of the first four digits equals the sum of the last four digits. What is the last date in that year with this property? Write it in the same format.
A rectangular sheet is divided into nine cells as shown. What is the minimum number of colors needed to color every cell so adjacent cells have different colors?
The even positive integers 2,4,6,8,...,2016 fill the five-column table shown, leaving one blank cell after every three filled cells. Which column contains 2016?
The diagram shows 24 pigeons, one per occupied cell. What is the minimum number of pigeons that must move to other empty cells, not necessarily neighboring ones, so every row and every column contains the same number?
Dung places all his marbles into seven boxes in a row, at least two per box. The product of the marble counts in any three consecutive boxes is 60. If the second box has 4 marbles, what is the greatest possible total?
The Olympic flag shows five circles intersecting at eight points. If the circles are moved so no two coincide, what is the maximum number of intersection points?
A bag contains 25 marbles in three colors: blue, red, yellow. Drawing 21 without looking is necessary to guarantee all three colors. What is the greatest possible number of yellow marbles?