Electricity, water and gas are measured with meters. The amount used in a month is found by subtracting the first reading from the last one. The payment is found by multiplying the amount used by the price of one unit (the rate). Rates change over time, so in problems we give the price as a condition. A family budget is a table of monthly income and expenses: subtracting the expenses from the income gives the savings (or the shortfall). Saving electricity, water and gas lowers family costs and protects nature. Do not touch meters or wires yourself; write down the reading together with an adult.
Worked examples
The meter showed 8 420 at the start of the month and 8 560 kWh at the end. Use: 8 560 − 8 420 = 140. If 1 kWh costs 300 so‘m (an assumed price), the payment is 140 · 300 = 42 000 so‘m.
Income is 3 600 000 so‘m, expenses are 3 150 000 so‘m. Savings: 3 600 000 − 3 150 000 = 450 000 so‘m.
Class activity
“Family saving”: with adults, write 3 ways to save water or electricity at home (for example, switching off unneeded lights) and try one of them for a week.
Practice
1
A meter changed from 12 340 to 12 520 and one unit costs 300 so‘m. What is the payment (so‘m)?
54000
2
25 units of electricity were wasted in a month at 300 so‘m each. How much money was wasted (so‘m)?
7500
3
Income is 4 200 000 and expenses are 3 850 000 so‘m. How much was saved (so‘m)?
350000
4
Why is it useful for a family to plan a budget in advance?
Expenses can be planned according to income, so running short of money is avoided.