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Unit review
Textbook: Part 4, pp. 87–88
GoalFinal review of sets, area, units of time and word problems.
New words
intersection · kesishmaarea · yuzunits of time · vaqt birliklariword problem · matnli masala
Explanation
Let us review. The intersection of sets A ∩ B consists of the common elements. We find the area of a composite shape by splitting it into rectangles and adding their areas. Units of time: 1 minute = 60 seconds, 1 hour = 60 minutes, 1 day = 24 hours, 1 week = 7 days. In a word problem we first decide what is asked and then what is known.
Worked examples
2 min 15 s = 2 × 60 + 15 = 135 s. 3 h 20 min = 3 × 60 + 20 = 200 min. 2 weeks 3 days = 2 × 7 + 3 = 17 days.
An L-shaped figure consists of rectangles 6 cm × 3 cm and 2 cm × 2 cm. Its area is 6 × 3 + 2 × 2 = 18 + 4 = 22 cm².
Class activity
“Final relay”: a four-stage relay – set intersection, area, time, word problem. Each group member solves one task at the board and passes the turn on.
Practice
1
A is the set of natural multiples of 5 up to 30 and B the set of natural multiples of 6 up to 30. Write A ∩ B.
{30}
2
How many minutes is 1 hour 45 minutes?
105
3
How many hours are in 4 days?
96
4
A rectangle 8 cm long and 5 cm wide is divided into two equal parts. What is the area of each part in cm²?
20
5
Bobur wants to save 180 000 sum for a bookshelf. He gets 12 000 sum each day, spends 3 000 sum and saves the rest. In how many days will he save 180 000 sum?
20