The table shows how the lengths of four pet lizards are changing over time.

Question

Time
(years) Lizard Name and Length (centimeters)
Chuck Betty Snapper Rocky
0 9 7 12 11
1 10 8 14 14
2 12 10 17 17
3 16 13 19 20
4 24 17 22 23
Which lizard is growing at a constant rate?

A.
Chuck

B.
Betty

C.
Snapper

D.
Rocky

Answer 1

To determine which lizard is growing at a constant rate, we need to examine the growth of each lizard over the years. A constant rate means that the length increases by the same amount each year.

Let's calculate the yearly growth for each lizard:

Chuck:

• Year 0 to 1: 10 - 9 = 1 cm
• Year 1 to 2: 12 - 10 = 2 cm
• Year 2 to 3: 16 - 12 = 4 cm
• Year 3 to 4: 24 - 16 = 8 cm

Betty:

• Year 0 to 1: 8 - 7 = 1 cm
• Year 1 to 2: 10 - 8 = 2 cm
• Year 2 to 3: 13 - 10 = 3 cm
• Year 3 to 4: 17 - 13 = 4 cm

Snapper:

• Year 0 to 1: 14 - 12 = 2 cm
• Year 1 to 2: 17 - 14 = 3 cm
• Year 2 to 3: 19 - 17 = 2 cm
• Year 3 to 4: 22 - 19 = 3 cm

Rocky:

• Year 0 to 1: 14 - 11 = 3 cm
• Year 1 to 2: 17 - 14 = 3 cm
• Year 2 to 3: 20 - 17 = 3 cm
• Year 3 to 4: 23 - 20 = 3 cm

Summary of growth:

• Chuck: Growth is not constant (1, 2, 4, 8 cm).
• Betty: Growth is not constant (1, 2, 3, 4 cm).
• Snapper: Growth is not constant (2, 3, 2, 3 cm).
• Rocky: Constant growth of 3 cm per year.

The lizard that is growing at a constant rate is:

D. Rocky