21
Sets and data
Textbook: Part 1, lesson 21, pp. 66–68
GoalUnderstand sets, their elements and data; read data from a table.
New words
set · to‘plamelement (member) · elementdata · ma’lumottable · jadval
Explanation
A set is a group of objects that share a property. The objects in a set are its elements. A set is written in curly brackets: A = {2, 4, 6, 8}. The order of elements does not matter and an element is not written twice. Collected numbers, names and other information are called data; putting them in a table makes them easier to read and work with.
Worked examples
The set of one-digit even natural numbers is A = {2, 4, 6, 8}. It has 4 elements.
Table: Monday – income 18 000, spending 9 000; Tuesday – 14 000 and 10 000; Wednesday – 11 000 and 11 000. Savings: 9 000, 4 000 and 0 sum.
Class activity
“Build a set”: the teacher names a property (“two-digit multiples of 5”) and children write the elements of that set on the board.
Practice
1
Write the set of two-digit multiples of 20.
{20, 40, 60, 80}
2
How many elements does the set of natural multiples of 4 less than 15 have?
3
3
Which of 12, 18, 24, 31, 36 does not belong to the set of multiples of 6?
31
4
From the table: Monday – income 18 000, spending 9 000; Tuesday – 14 000 and 10 000; Wednesday – 11 000 and 11 000. How many sum were saved in the three days?
13000