Lesson 7: Practice Problems

Problem 1

What is the final elevation if

A bird starts at 20 m and changes 16 m?
A butterfly starts at 20 m and changes -16 m?
A diver starts at 5 m and changes -16 m?
A whale starts at -9 m and changes 11 m?
A fish starts at -9 meters and changes -11 meters?

Problem 2

One of the particles in an atom is called an electron. It has a charge of -1. Another particle in an atom is a proton. It has charge of +1. The charge of an atom is the sum of the charges of the electrons and the protons. A carbon atom has an overall charge of 0, because it has 6 electrons and 6 protons and $- 6 + 6 = 0$ . Find the overall charge for the rest of the elements on the list.

	charge from electrons	charge from protons	overall charge
carbon	$- 6$	$+ 6$	$0$
neon	$- 10$	$+ 10$
oxide	$- 10$	$+ 8$
copper	$- 27$	$+ 29$
tin	$- 50$	$+ 50$

Problem 3

Add.

$14.7 + 28.9$
$- 9.2 + 4.4$
$- 81.4 + (- 12)$
$51.8 + (- 0.8)$

Problem 4 From Unit 7 Lesson 5

Select all the true statements.

$- 5 < | - 5 |$
$| - 6 | < - 5$
$| - 6 | < 3$
$4 < | - 7 |$
$| - 7 | < | - 8 |$

Problem 5 From Unit 6 Lesson 5

Last week, the price, in dollars, of a gallon of gasoline was $g$ . This week, the price of gasoline per gallon increased by 5%. Which expressions represent this week’s price, in dollars, of a gallon of gasoline? Select all that apply.

$g + 0.05$
$g + 0.05 g$
$1.05 g$
$0.05 g$
$(1 + 0.05) g$

Problem 6 From Unit 6 Lesson 7

A family goes to a restaurant. When the bill comes, this is printed at the bottom of it:

Gratuity Guide For Your Convenience:
15% would be $4.89
18% would be $5.87
20% would be $6.52

How much was the price of the meal? Explain your reasoning.