The table shows David's average water use for one day:
Calculate the amount of water David is using per day.
Calculate the amount of water David uses in a week.
If David only used the washing machine once a week, find the amount of water he would use in a week.
State the percentage of David's daily water usage that is taken up by the washing machine. Round your answer to the nearest percentage.
If water costs \$2.90 \text{ per kL}, how much would David have to pay per day?
Construct a column graph for his daily water usage.
| Usage | Litres per day |
|---|---|
| \text{Dishwasher} | 31 |
| \text{Washing Machine} | 30 |
| \text{Gardening} | 12 |
| \text{Toilet} | 28 |
| \text{Shower} | 53 |
A water saving shower head uses 60\% of the water an ordinary shower head does.
If Sharon uses 5.8 \text{ kL} of water to shower each month, calculate the amount of water she would save with a water saving shower head.
If water costs \$1.9 a kilolitre, determine how much money Sharon would save.
The cost of water has risen from \$1.20 per litre last year to \$2.10 per litre this year.
Under the old price, determine how much would Eileen pay if she uses 489 \text{ L} of water.
If Eileen uses the same amount of water this year, how much will she have to pay under the new price?
If Eileen wants to pay the same total amount this year as she did last year, calculate the amount of water she should use, correct to one decimal place.
A family received an electricity bill of \$405 in the last quarter, with electricity charged at 22.5 cents per \text{kWh}. They are considering installing a new 2.8 \text{ kW} air conditioning unit and estimate that they’ll use it for 9 hours each day.
Calculate the amount of energy they use in the last quarter (in \text{kWh}).
Calculate the amount of energy the air conditioning unit will generate in the next quarter (in \text{kWh}). Assume there are 90 days in a quarter.
How much would the air conditioning unit add to their next quarterly electricity bill?
The following table shows the monthly charges listed for Deborah’s natural gas account:
Deborah uses exactly 5000 \text{ MJ} in January. Find the total monthly cost.
In February, Deborah uses 13\,500 \text{ MJ} more than she did in January. By how much does her total monthly cost increase?
Find the total monthly cost that Deborah has to pay on her gas bill in February.
Calculate the average charge that Deborah paid per \text{MJ} of gas in February.
| Amount used | Charges |
|---|---|
| \text{First }5000 \text{ MJ} | \$0.0192 / \text{MJ} |
| \text{Next }13\,500\text{ MJ} | \$0.0155 / \text{MJ} |
| \text{Supply Fee} | \$80.00 |
The table shows a family’s energy consumption in percentages:
| Cooking | Water heating | Appliances | Heating and cooling |
|---|---|---|---|
| 6\% | 20\% | 30\% | 44\% |
In the last quarter, the family’s electricity bill showed a balance of \$203.6772 and 1080 \text{ kWh} of electricity use. Currently all their energy usage is electricity based.
Find the cost of electricity per \text{kWh}. Do not round your answer.
Gas energy costs 3.549 cents per \text{MJ}. If they convert the water heating from electricity to gas energy, how much can they expect to save in the next quarter? Note that \\ 1 \text{ kWh} = 3.6 \text{ MJ}.
Consider Sally's water bill below:
State the total amount due.
State the length of the billing period.
State the total supply charge (fixed charges).
What percentage of the total amount due are supply charges? Round your answer to the nearest percent.
On average, how many litres of water has Sally used per day during the billing period? Round your answer to the nearest litre.
NSW Water has informed Sally that on her next billing period the cost of water is increasing by 12 cents per \text{kL}. If Sally’s total water usage over the next billing period remains the same, how much extra will she be paying on her bill?
The following table shows details from an electricity bill of a small business:
Calculate the amount for the off peak electricity usage.
Calculate the supply charge for the 28 days of the billing period.
Calculate the total amount due.
If a 10\% GST is applied to the total amount due, calculate the final total for the bill.
The following information is taken from Joanne's latest gas bill:
State the type of plan Joanne is on with the energy company.
State the unique number identifying Joanne’s address as a gas connection point.
State the unique number identifying Joanne’s gas meter.
Given that the meter readings are in cubic metres, write down the amount of gas used for the supply period in cubic metres.
The amount of gas used in megajoules can be found by multiplying the gas used in cubic metres by the heating value and conversion factor. Find the amount of gas used in megajoules. Round your answer to two decimal places.
What word on the bill may indicate to Joanne that her gas meter readings may not be correct and why might this be the case?
During what time period is the energy company next planning to read Joanne's meter?
The details of Holly's internet bill and billing history is given below:
Using the current bill and bill history, calculate Holly's predicted weekly expenditure on internet.
Use the fact that there are 52 weeks in a year.
| Months | Bill charge |
|---|---|
| \text{August} | \$29.30 |
| \text{July} | \$37.50 |
| \text{June} | \$30.00 |
| \text{May} | \$45.00 |
| \text{April} | \$23.20 |
| \text{March} | \$33.60 |
| \text{February} | \$47.10 |
| \text{January} | \$38.30 |
| \text{December} | \$25.10 |
| \text{November} | \$18.70 |
| \text{October} | \$30.00 |
Consider the council rates bill shown below:
State the value of Brian's property in dollars.
How much did Brian pay in rates for the value of his property?
Calculate the percentages of the total amount of the bill attributed to the following, rounding your answers to the nearest percent:
Residential value.
Stormwater management.
Domestic waste management.
A NSW electricity company has a product called Green Power which allows customers to have a certain percentage of their electricity generated from renewable sources.
Bill currently pays a flat rate of \$0.3445 \text{ per kWh} for his electricity. Bill would like to help support Australia’s renewable energy industry. He understands that if he switches to 100\% Green Power the cost of his electricity will increase by 5 \text{c per kWh}.
On his last electricity bill, Bill's average daily electricity consumption was 8.5 \text{ kWh}. Calculate the cost of Bill's average daily electricity consumption on his last bill.
Work out the cost of his average electricity consumption for a week.
Calculate the cost of Bill's average weekly electricity consumption if he switches to using 100\% Green Power.
How much extra would Joe be paying for electricity each week, if he uses 100\% Green Power?
Bill doesn't wish to pay more than \$5 per week on average if he switches to Green Power. Can Bill make the switch?
Sophia is currently on a fixed rate electricity plan and is considering switching to a flexible plan where her electricity usage is charged different rates depending on the time of day. Sophia estimates she uses approximately 9.5 \text{ kWh} of electricity per day.
Flexible plan
| Charge type | Rate |
|---|---|
| \text{Peak usage} | 58.79 \text{ cents per kWh} |
| \text{Shoulder usage} | 26.72 \text{ cents per kWh} |
| \text{Off peak usage} | 16.26 \text{ cents per kWh} |
| \text{Supply} | 89.76 \text{ cents per kWh} |
Fixed rate plan
| Charge type | Rate |
|---|---|
| \text{Usage} | 31.41 \text{ cents per kWh} |
| \text{Supply} | 89.76 \text{ cents per kWh} |
If Sophia stays on the fixed rate plan, find her total electricity costs for a 92-day period.
Sophia estimates that during an average day she would use 2.5 hours of peak time, 5 hours of shoulder time and 2 hours of off peak time electricity. Calculate her total electricity costs for a 92-day period on the flexible plan in dollars.
Which plan will give Sophia the most savings?
The Wu family are conservative users of electricity and have solar panels installed on their roof. Their electricity usage is measured by a 'smart meter' which sends usage data direct to the energy company. It is why they have no meter readings on their bill. They are on a time of use plan called 'Flexible Saver' which have the rates given. They also get a solar feed-in credit on their bill for unused solar electricity that is fed back into the grid. Their rates are summarised in the tables below:
| Charge type | Rate |
|---|---|
| \text{Peak usage} | 53.01 \text{ cents per kWh} |
| \text{Shoulder usage} | 14.42 \text{ cents per kWh} |
| \text{Off peak usage} | 23.79 \text{ cents per kWh} |
| \text{Supply} | 96.85 \text{ cents per day} |
| Credit type | Rate |
|---|---|
| \text{Solar feed in} | 9 \text{ cents per kWh} |
Their usage summary and solar feed summary are given below:
Usage summary
Period: 28 Jun 18 to 26 Sep 18 (91 days)
| \text{Meter no.} | \text{Usage type} | \text{Previous read} | \text{Current read} | \text{Usage (kWh)} |
|---|---|---|---|---|
| 067458 | \text{Peak} | - | - | 113.173 |
| \text{Off peak} | - | - | 148.631 | |
| \text{Shoulder} | - | - | 281.399 |
Solar feed summary
Period: 28 Jun 18 to 26 Sep 18 (91 days)
| \text{Meter no.} | \text{Previous read} | \text{Current read} | \text{Export (kWh)} |
|---|---|---|---|
| 067458 | - | - | 233.347 |
Calculate the total usage cost for the billing period.
The energy company provides an 18\% discount on usage costs if the bill is paid on time. Calculate the revised usage cost if the Wu family pay before the due date of the bill.
Calculate the total supply cost for the billing period.
Hence, find the total electricity cost.
Find the total electricity cost after a 10\% GST is applied.
Find the total credit they receive from the solar electricity they fed back into the grid.
State the cost of the entire bill.
The pie graph shows the annual water usage in kilolitres for a household:
Calculate the amount of water that was used (in \text{kL}).
State the percentage of the total water usage that was taken up by the car, correct to one decimal place.
If the car required 20\% less water every year, calculate the amount of water that would be saved per year (in \text{kL}).
If water costs \$1.10 \text{ per kL}, how much does this household have to pay?
How much would the household pay if they used 20\% less water for the laundry but 10\% more for the shower?
A typical four person household uses the following energy consumption on average:
| Usage per day (kWh) | Usage for time period (kWh) | |
|---|---|---|
| Summer | 16.4 | 1495 |
| Autumn | 17.4 | 1589 |
| Winter | 19.5 | 1776 |
| Spring | 19.3 | 1757 |
| Year | 18.1 | 6617 |
If an electricity company charges \$0.245 \text{ per kWh}, calculate the cost of the electricity bill of a typical household for the entire season of Autumn.
If an electricity company charges \$0.235 \text{ per kWh}, calculate the yearly cost of the electricity bill of a typical household.
If an electricity company charges \$0.175 \text{ per kWh}, how much more would a typical household expect their electricity bill to cost in Spring than in Autumn?
Elena is preparing a budget. Her gas usage over the past year for each month is given on the following table:
Predict Elena's energy usage for the following month by using her average monthly energy usage. Round your answer to the nearest megajoule.
The fixed usage cost is \$0.028 \text{ per MJ} and the supply charge is \$18 each month. These rates are inclusive of GST. Find the cost of Sophia's expected gas bill for the next month.
Elena has accounted for \$90 per month for her gas bill in her budget. Has she budgeted enough?
| Month | Usage |
|---|---|
| \text{March 2019} | 2430 \text{ MJ} |
| \text{February 2019} | 2436 \text{ MJ} |
| \text{January 2019} | 2351 \text{ MJ} |
| \text{December 2018} | 2447 \text{ MJ} |
| \text{November 2018} | 2354 \text{ MJ} |
| \text{October 2018} | 2444 \text{ MJ} |
| \text{September 2018} | 2353 \text{ MJ} |
| \text{August 2018} | 2448 \text{ MJ} |
| \text{July 2018} | 2434 \text{ MJ} |
| \text{June 2018} | 2361 \text{ MJ} |
| \text{May 2018} | 2362 \text{ MJ} |
| \text{April 2018} | 2444 \text{ MJ} |
Consider the following households and the approximate gas usage:
Households with 1 - 2 residents use on average 3100 \text{ MJ} of gas per quarter.
Households with 3 - 4 residents use on average 5400 \text{ MJ} of gas per quarter.
Households with 5 or more residents use on average 6400 \text{ MJ} of gas per quarter.
If gas is charged by the gas company at \$0.027\,51 \text{ per MJ} for the first 1220 \text{ MJ}, and \$0.022\,83 \text{ per MJ} for the remaining, calculate the quarterly bill of the average household with 3 to 4 residents.
After a severe drought in February 2018, the city of Cape Town in South Africa implemented emergency water restrictions for all residents. Each resident was limited to just 50 \text{ L} of water per day.
One estimate for the average daily water consumption per person in Australia is 340 \text{ L per }day. If we assume a person needs 3 \text{ L} of water a day for drinking in both cases, describe how you could save water if the same restrictions were imposed in Australia.
Cape Town recommends that 10 \text{ L} of water should be used for showering and 3 \text{ L} for drinking. What is the percentage difference of their daily water limit between the amount used for showering versus drinking?