# Lesson 6

Changing Temperatures

### Problem 1

Draw a diagram to represent each of these situations. Then write an addition expression that represents the final temperature.

1. The temperature was $$80 ^\circ \text{F}$$ and then fell $$20 ^\circ \text{F}$$.
2. The temperature was $$\text-13 ^\circ \text{F}$$ and then rose $$9 ^\circ \text{F}$$.
3. The temperature was $$\text-5 ^\circ \text{F}$$ and then fell $$8 ^\circ \text{F}$$.

### Problem 2

1. The temperature is -2$$^\circ \text{C}$$. If the temperature rises by 15$$^\circ \text{C}$$, what is the new temperature?
2. At midnight the temperature is -6$$^\circ \text{C}$$. At midday the temperature is 9$$^\circ \text{C}$$. By how much did the temperature rise?

### Problem 3

Complete each statement with a number that makes the statement true.

1.  _____ < $$7^\circ \text{C}$$
2.  _____ < $$\text- 3^\circ \text{C}$$
3.  $$\text- 0.8^\circ \text{C}$$ < _____ < $$\text- 0.1^\circ \text{C}$$
4.  _____ > $$\text- 2^\circ \text{C}$$
(From Unit 7, Lesson 1.)

### Problem 4

Match the statements written in English with the mathematical statements. All of these statements are true.

(From Unit 7, Lesson 5.)

### Problem 5

Evaluate each expression.

• $$2^3 \boldcdot 3$$
• $$\frac{4^2}{2}$$
• $$3^1$$
• $$6^2 \div 4$$
• $${2^3}-{2}$$
• $${10^2}+{5^2}$$
(From Unit 4, Lesson 13.)

### Problem 6

Decide whether each table could represent a proportional relationship. If the relationship could be proportional, what would be the constant of proportionality?

1. The number of wheels on a group of buses.

number of buses number of wheels wheels per bus
5 30
8 48
10 60
15 90
2. The number of wheels on a train.

number of train cars number of wheels wheels per train car
20 184
30 264
40 344
50 424
(From Unit 5, Lesson 4.)