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Everyday maths 2 (Wales)

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# 5 Negative numbers

Negative numbers come into play in two main areas of life: money and temperature. Watch the animations below for some examples.

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## Activity 11: Negative and positive temperature

1. The table below shows the temperatures of cities around the world on a given day

Table 5
LondonOsloNew YorkKrakówDelhi
4˚C−12C7˚C−3˚C19˚C
•

• a.Which city was the warmest?

• b.Which city was the coldest?

• c.What is the difference in temperature between the warmest and coldest cities?

1.

• a.Delhi was the warmest city as it has the highest positive temperature.

• b.Oslo was the coldest city as it has the largest negative temperature.

• c.The difference between the temperatures in these cities is 31˚C.

From 19˚C down to 0˚C is 19˚C and then you need to go down a further 12˚C to get to −12˚C.

1. Look at this bank statement.

Figure 6 A bank statement
• a.On which days was Sonia Cedar overdrawn, and by how much?

• b.How much money was withdrawn between 9 and 11 of October?

• c.How much was added to the account on 15 October?

1.

• a.The minus sign (−) indicates that the customer is overdrawn, i.e. owes money to the bank.

The amount shows how much they owe. So Sonia Cedar was overdrawn on 11 October by £20 and by £50 on 21 October.

• b.£120 was withdrawn on 11 October.

The customer had £100 in the account and must have withdrawn another £20 (i.e. £100 + £20 = £120 in total) in order to be £20 overdrawn.

• c.The customer owed £20 and is now £70 in credit, so £90 must have been added to the account.

1. Look at the table below showing a company’s profits over 6 months.

Hint: a negative profit means that the company made a loss.

Table 6
MonthProfit (£000)
January166
February182
March−80
April124
May98
June−46
BalanceHighlighted
•

• a.Which month had the greatest profit?

• b.Which month has the greatest loss?

• c.What was the overall balance for the six months?

Hint: start by calculating the total profits and the total losses.

1.

• a.February had the largest profit with £182 000 (remember to look at the column heading which shows that the figures are in 000s – thousands).

• b.March showed the greatest loss at £80 000.

• c.To calculate the overall balance you need to first calculate the total profits and the total losses. To calculate the profits you need to do this calculation:

• 166 + 182 + 124 + 98 = 570

So the profit was £570 000.

Next you need to calculate the total losses; two months showed a loss so you need to add these values:

• 80 + 46 = 126 so the losses over the six months were £126 000.

Now you can calculate the overall balance by subtracting the losses from the profits:

• £570 000 − £126 000 = £444 000

This is a positive value so it means the company made an overall profit of £444 000.

## Summary

In this section you have:

• learned the two main contexts in which negative numbers arise in everyday life – money (or debt!) and temperature

• practised working with negative numbers in these contexts.