121
Price, quantity and cost
Textbook: Part 4, lesson 121, pp. 34–36
GoalThe ideas of price, quantity and cost; finding the cost, the price and the quantity.
New words
price · narxquantity · miqdorcost (total) · qiymatsum per kilogram · so‘m/kg
Explanation
The price is the money paid for one unit (1 piece, 1 kg, 1 m). The quantity tells how many pieces, kilograms or metres were bought. The cost is the total money paid for the whole purchase. A price is written in units such as sum/piece, sum/kg, sum/m. To find the cost we multiply the price by the quantity; to find the price we divide the cost by the quantity; to find the quantity we divide the cost by the price.
Worked examples
1 kg of apples costs 11 000 sum (the price is 11 000 sum/kg). The cost of 6 kg of apples: 11 000 × 6 = 66 000 sum.
5 notebooks cost 20 000 sum. The price of one notebook: 20 000 : 5 = 4 000 sum/piece. With 36 000 sum we can buy 36 000 : 4 000 = 9 notebooks.
Class activity
“Class shop”: children are sellers and buyers with items (notebook, pencil, eraser) that have price tags. The buyer works out the cost for the chosen quantity and the seller checks it.
Practice
1
1 kg of grapes costs 15 000 sum/kg. What is the cost of 4 kg of grapes in sum?
60000
2
7 pencils cost 21 000 sum. How many sum does one pencil cost?
3000
3
One box of juice costs 9 000 sum. How many boxes can be bought for 54 000 sum?
6
4
One loaf of bread costs 3 500 sum. What is the cost of 12 loaves in sum?
42000