Lesson 3

Changing Elevation

Let's solve problems about adding signed numbers.

Problem 1

What is the final elevation if

  1. A bird starts at 20 m and changes 16 m?
  2. A butterfly starts at 20 m and changes -16 m?
  3. A diver starts at 5 m and changes -16 m?
  4. A whale starts at -9 m and changes 11 m?
  5. 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 \(\text- 6 + 6 = 0\). 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.

\(14.7 +28.9\)

\(\text-9.2 + 4.4\)

\(\text-81.4 + (\text-12)\)

\(51.8 + (\text-0.8)\)

Problem 4

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.

A:

\(g + 0.05\)

B:

\(g + 0.05g\)

C:

\(1.05g\)

D:

\(0.05g\)

E:

\((1+0.05)g\)

(From Unit 4, Lesson 8.)

Problem 5

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

  1. Annie’s Attic is giving away $5 off coupons.

    original price sale price
    $15 $10
    $25 $20
    $35 $30

  2. Bettie's Boutique is having a 20% off sale.

    original price sale price
    $15 $12
    $25 $20
    $35 $28
(From Unit 2, Lesson 7.)