A chart maps 0 to 0, 1 to 2, 2 to 4, 3 to 6. Assuming linear progression, what is the value at 4?

• A. 6
• B. 7
• C. 8
• D. 10

Answer: (C)

This question tests recognizing a linear relationship with a constant rate of change. Each step in the input adds 2 to the output, so the rule is y = 2x. Using this, at input 4 the value is 8. The other options don’t fit this steady pattern: 6 would correspond to an input of 3, 7 breaks the constant increase, and 10 would correspond to an input of 5.