Lesson 2: Practice Problems

Problem 1

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

Problem 2

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

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

Problem 3 From Unit 5 Lesson 1

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

$< 7^{\circ} C$
$< - 3^{\circ} C$
$- {0.8}^{\circ} C <$ $< - {0.1}^{\circ} C$
$> - 2^{\circ} C$

Problem 4 From Unit 2 Lesson 7

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

The number of wheels on a group of buses.
number of buses
number of wheels
wheels per bus
$5$
$30$
$8$
$48$
$10$
$60$
$15$
$90$
The number of wheels on a train.
number of train cars
number of wheels
wheels per train car
$20$
$184$
$30$
$264$
$40$
$344$
$50$
$424$

number of buses	number of wheels	wheels per bus
$5$	$30$
$8$	$48$
$10$	$60$
$15$	$90$

number of train cars	number of wheels	wheels per train car
$20$	$184$
$30$	$264$
$40$	$344$
$50$	$424$

Problem 5 From Unit 4 Lesson 7

Noah was assigned to make 64 cookies for the bake sale. He made 125% of that number. 90% of the cookies he made were sold. How many of Noah’s cookies were left after the bake sale?