Money Calculations

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Notes

Currencies and Notation

Common currencies: US Dollars ($), Pounds (£), Euros (€).
Always write money to **two decimal places** (e.g., £1.40, $5.00).
For large amounts, rounding to nearest pound/dollar may be appropriate.
Check the currency used in the question and match it in your answer.

Basic Operations with Money

**Total** or **sum** means add amounts.
**Difference** or **increase/decrease** involves subtraction.
**Exchange rates** require multiplication or division.
Read keywords carefully to decide the operation.

Calculating Total Cost

Multiply quantity by unit price to find cost of items.
Add all individual costs to get the total.
Example: 3 tins at $15.95 each = $47.85; add other items for total.
Always write down intermediate steps to avoid errors.

Calculating Change

Change = amount paid − total cost.
Subtract the total from the note/coin given.
Example: $10 − $6.80 = $3.20 change.
Ensure the answer is in the correct currency and decimal places.

Deals and Discounts

**'Buy 3 get 1 free'** or **'4 for price of 3'** reduce cost per item.
Calculate total cost after deal, then divide by number of people.
Example: 12 burgers, deal 4 for price of 3 → pay for 9 burgers.
Work out the price each person pays from the reduced total.

Profit and Percentage

**Profit** = selling price − cost price.
**Percentage profit** $= (profit / cost) \times 100\%$ .
To find selling price with profit: cost $\times (1 + profit\%)$ .
Example: cost $1.50, 60% profit → selling price = $1.50 $\times 1.60 =$ $2.40.

Wages and Hourly Pay

Total $pay =$ hours worked × hourly rate.
**Overtime** often paid at 1.5 times (time‑and‑a‑half) the usual rate.
Add regular pay and overtime pay for total earnings.
Example: 34 h at $8.25/h + 8 h at $12.375/h = $379.50.

Best Value Comparisons

Find **unit cost** (price per kg, per litre, etc.) to compare sizes.
The smallest unit cost gives the best value.
Show working: divide price by quantity for each option.
Example: 20L bag $10 → $0.50/L; 40L bag $18 → $0.45/L → 40L is better.

Rounding and Accuracy

Keep all decimal places during calculations; round only the final answer.
For money, round to **two decimal places** unless context says otherwise.
If a price is given to more than 2 d.p. (e.g., £1.579), use it fully in working.
Final answer: e.g., £119.455 → £119.46.

Common Question Types

**Shopping bills**: complete missing costs and find total.
**Change from a note**: subtract total from note value.
**Deposit and instalments**: subtract deposit, divide remainder by number of payments.
**Percentage of tickets sold**: $(sold / total) \times 100\%$ .

Calculating Total Cost and Change

Deal: 4 for Price of 3

Profit Calculation

Parking Cost Calculation

Practice questions

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1.A car costs $18160. A deposit of $6460 is paid, and the rest in 24 equal monthly payments. What is each monthly payment?
Easy
- A$487.50
- B$756.67
- C$1170.00
- D$757.50
2.Henry buys 3 tins of paint at $15.95 each, 2 brushes at $7.50 each, and 1 roll of tape at $2.90. What is the total cost?
Easy
- A$65.75
- B$63.25
- C$62.35
- D$66.85
3.Sue has one tea ($2.35) and one cake ($4.45). How much does she pay?
Easy
- A$6.80
- B$6.70
- C$7.80
- D$6.90
4.Derrick has one coffee ($3.40) and two biscuits ($0.85 each). How much change from a $10 note?
Easy
- A$4.90
- B$5.10
- C$5.90
- D$4.10
5.Jodi swims 22 lengths and receives $15 per length. How much money does she raise?
Easy
- A$330
- B$37
- C$300
- D$350
6.You buy one portion of chicken wings (£5.49) and one water (£1.50). How much change from a £10 note?
Medium
- A£3.01
- B£2.99
- C£3.99
- D£2.01
7.A bill: 2.5 kg potatoes at $1.12 per kg, and some bananas at $1.05 per kg. Total is $4.69. How many kg of bananas?
Medium
- A1.8 kg
- B2.0 kg
- C1.5 kg
- D2.2 kg
8.Rangan buys 3.6 kg potatoes and 2.8 kg leeks. Total cost $13.72. Leeks cost $2.65 per kg. Find cost of 1 kg potatoes.
Hard
- A$1.40
- B$1.20
- C$1.60
- D$1.50

Summary

## Money Calculations - Quick Revision ### Key Skills - **Total/Sum**: Add costs. - **Difference/Change**: Subtract. - **Multiply/Divide**: For unit prices, exchange rates, or splitting payments. - **Round to 2 decimal places** for dollars/pounds/euros (e.g., $1.40 not $1.4). Use given decimals in working, round only final answer. ### Common Question Types - **Shopping bills**: Multiply quantity by price, add items. - **Change from a note**: Subtract total from amount given. - **Equal payments**: Subtract deposit, divide remainder by number of payments. - **Best value**: Compare price per unit (e.g., per kg or per litre). - **Percentage of total**: (part / total) × 100. - **Profit**: Selling price = cost + (percentage profit × cost). - **Overtime pay**: Overtime rate = usual rate × 1.5 (or given multiplier). - **Deals**: e.g., "4 for price of 3" means pay for 3, get 4. - **Time & cost**: Count full days (part days count as full). - **Fuel cost**: litres needed = distance / km per litre; cost = litres × price per litre. ### Examples from Past Papers - **Car purchase**: $18160 - $6460 deposit = $11700; $11700 ÷ 24 = $487.50 per month. - **Café bill**: Tea $2.35 + Cake $4.45 = $6.80; change from $10: $10 - $6.80 = $3.20. - **Instrument total**: String $4716, Woodwind 15×$217=$3255, Brass 12×$221=$2652; total = $10623; 65% given, so need 35%: 0.35×$10623=$3718.05. - **Parking**: 17 Jul (Tue) 10:00 to 28 Jul (Sat) 17:00. Count full days: Tue 17 to Fri 27 = 11 weekdays (Mon-Fri) + Sat 21 & Sat 28 (2 Saturdays) + Sun 22 & Sun 29? Actually 28 Jul is Saturday, so days: 17-20 (Tue-Fri) = 4 weekdays, 21 (Sat) = 1 weekend, 22 (Sun) = 1 weekend, 23-27 (Mon-Fri) = 5 weekdays, 28 (Sat) = 1 weekend. Total weekdays = 4+5=9, weekends = 1+1+1=3. Cost = 9×$14 + 3×$8 = $126+$24=$150. - **Overtime**: Harriet works 34 hrs at $8.25 = $280.50; extra 8 hrs at 1.5×$8.25=$12.375 each = $99; total = $379.50. - **Fuel**: 320 km ÷ 10 km/L = 32 L; cost = 32 × £1.50 = £48. - **Best value**: Compare price per kg for different bag sizes. ### Key Terms

Key terms

Deposit: An initial payment made when buying something, with the remainder paid later.
Monthly payment: Equal amounts paid each month to settle a debt.
Change: The amount returned after paying with more than the cost.
Total cost: The sum of all individual costs.
Percentage: A fraction out of 100, often used to express a portion of a total.
Profit: The amount gained from selling something, calculated as selling price minus cost price.
Overtime: Hours worked beyond normal hours, often paid at a higher rate (e.g., 1.5 times).
Best value: The option that gives the lowest cost per unit (e.g., per kg).
Exchange rate: The value of one currency in terms of another.

Slides

Money Calculations Overview

Money calculations involve adding, subtracting, multiplying, and dividing amounts in a given currency.
Common currencies include US Dollars ($), Pounds (£), and Euros (€).
Always round final answers to two decimal places unless told otherwise.

What is the usual number of decimal places for amounts in dollars or pounds?

Adding and Subtracting Money

To find the total cost, add all items together.
To find change, subtract the cost from the amount paid.
Example: If you buy a tea ($2.35) and a cake ($4.45), total = $6.80. Change from $10 = $3.20.

Sue has one tea ($2.35) and one cake ($4.45). She pays $____. Change from $10 is $____.

Multiplying Money

To find the cost of multiple identical items, multiply the unit price by the quantity.
Example: 3 tins of paint at $15.95 each cost $3 \times 15.95 =$ $47.85.
Always write the answer with two decimal places.

What is the cost of 6 burgers at $4.79 each?

$28.74
$28.70
$28.74
$28.80

Deals and Discounts

Sometimes deals like '4 for the price of 3' reduce the cost.
For 12 burgers with a '4 for 3' deal, you pay for 9 burgers (3 sets of 4).
Total cost $= 9 \times$ unit price. Then divide by number of people to find each person's share.

Which of these are true about the '4 for the price of 3' deal?

You pay for 4 items and get 1 free.
For 12 items, you pay for 9.
The cost per item is reduced.

Calculating Change

Change = amount given - total cost.
Example: Derrick has one coffee ($3.40) and two biscuits ($0.85 each). Total $= 3.40 + 1.70 = 5.10$ . Change from $10 = $4.90.

Derrick has one coffee ($3.40) and two biscuits ($0.85 each). Total cost = $____. Change from $10 = $____.

Working with Tables

Sometimes you need to complete a bill or table by multiplying and adding.
Example: 2.5 kg potatoes at $1.12 per $kg = 2.5 \times 1.12 =$ $2.80.
Then add other items to find the total.

Complete: 2.5 kg potatoes at $1.12 per kg costs:

$2.80
$2.50
$3.00
$2.75

Percentage of an Amount

To find a percentage of a total, multiply the total by the percentage (as a decimal).
Example: 65% of total cost $= 0.65 \times$ total.
To find how much more is needed, subtract the amount given from the total.

Which statements are true?

65% of $100 is $65.
To find 65%, multiply by 0.65.
If 65% is given, the remaining is 45%.

Profit and Selling Price

Profit percentage is based on the cost price.
Selling price = cost price + profit.
Example: Cost $1.50, 60% profit → profit $= 0.60 \times 1.50 =$ $0.90, selling price = $2.40.

A pineapple costs $1.50. With 60% profit, what is the selling price?

$2.10
$2.40
$2.00
$2.50

Hourly Wages and Overtime

Weekly $pay =$ hours worked × hourly rate.
Overtime is often paid at 1.5 times the usual rate.
Total $pay =$ normal pay + overtime pay.

Harriet works 34 hours at $8.25 per hour. Weekly $pay =$ $____. If she works 8 extra hours at 1.5 times, overtime $pay =$ $____. Total = $____.

Best Value Comparisons

To find the best value, calculate the price per unit (e.g., per kg or per litre).
Compare unit prices; the lowest gives the best value.
Always show your working.

Which bag gives the best value? Bag A: 10kg for $15, Bag B: 5kg for $8.

Bag A
Bag B
Same
Cannot tell

Flashcards

Robert buys a car for $18160. He pays a deposit of $6460 and the rest in 24 equal monthly payments. Work out the amount of each monthly payment.

$487.50

Henry's shopping bill: 3 tins of paint at $15.95 each, 2 brushes at $7.50 each, 1 roll of tape at $2.90. Find the total cost.

$65.75

Sue has one tea ($2.35) and one cake ($4.45). Calculate how much she pays.

$6.80

Derrick has one coffee ($3.40) and two biscuits ($0.85 each). How much change from a $10 note?

$4.90

A music teacher buys 36 string instruments at $131 each, 15 woodwind at $217 each, 12 brass at $221 each. Complete the table and find total cost.

Woodwind cost: $3255; Brass cost: $2652; Total cost: $10623

The school is given 65% of the total cost ($10623). Find how much more money is needed.

$3718.05

Jodi swims 22 lengths and receives $15 per length. Calculate how much she raises.

$330

A burger costs £4.79. Work out the cost of 6 burgers.

£28.74

12 people want one burger each. Deal: four burgers for the price of three. Work out the price each person must pay.

£3.59

How much change from a £10 note if you buy one portion of chicken wings (£5.49) and one water (£1.50)?

£3.01

Johan buys 2 cups of tea ($2.20 each), 1 bottle of juice ($1.50), 1 bottle of water ($1.35). Calculate change from a $10 note.

$2.75

Complete the bill: 2.5 kg potatoes at $1.12 per kg, and ? kg bananas at $1.05 per kg, total $4.69. Find the cost of potatoes and weight of bananas.

Potatoes cost $2.80; Bananas weight 1.8 kg

A shop sells compost in three sizes. Which size gives the best value? (Size A: 20L $5, Size B: 50L $12, Size C: 80L $18)

Size C (80L for $18) gives the best value at $0.225 per litre.

Jeremy parks from 1000 Tuesday 17 July to 1700 Saturday 28 July. Charges: Mon-Fri $14/day, Sat-Sun $8/day, part days as full days. Find total cost.

$172

Jeremy buys a ring for $53 and a watch for $65. Change from $120?

Jodie (adult $15.30) and two children ($6.50 each) go to a match. Total cost of three tickets?

$28.30

Jodie buys two match programmes at $3.75 each. Change from a $10 note?

$2.50

540 tickets out of 630 are sold. Calculate the percentage of tickets sold.

85.7% (or 85.71%)

Match starts at 1455 and ends 1 hour 50 minutes later. Work out the end time.

1645

Jodie travels 66 km from 5pm to 6.12pm. Calculate average speed in km/h.

55 km/h

Apples cost 32 cents each. Suki buys 6 apples and pays with a $10 note. Change?

$8.08

Green grapes $3.10/kg, red grapes $2.80/kg. Total cost of 0.6 kg green and $\frac{3}{4}$ kg red?

$3.96

George spends $12 on fruit out of $75 on food. Percentage spent on fruit?

16%

Mr Lester buys pineapples for $1.50 each and makes 60% profit. Selling price?

$2.40

Nadira pays 6 people: 4 work 38 hours, 2 work 25 hours, all at $11.40/hour. Total weekly pay?

$2302.80

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