Question

1. Miguel is taking a quiz that contains 5 questions.

Each question is worth 20 points, with no partial
credit. If x represents the number of questions
answered correctly and y represents the number
of points awarded, this function can be
represented by the equation y = 20x.
What is a reasonable domain for this function?
A. x ≤ 5
B. 0≤x≤5
C. {0, 1, 2, 3, 4, 5}
D. {0, 20, 40, 60, 80, 100}

Answer 1

C. {0, 1, 2, 3, 4, 5}

Explanation:

There are 6 possible outcomes: 0 points (0 questions correct), 20 points (1 question correct), 40 points (2 questions correct), 60 points (3 questions correct), 80 points (4 questions correct) and 100 points (5 questions correct). The number of points is equal to the number of questions answered times 20. The x value can only be equal to the possible number of questions answered correctly: 0, 1, 2, 3, 4, 5.

A is incorrect because it includes negative numbers and decimals. Decimal values aren't possible because no partial credit is given for the questions. Negative numbers are incorrect because you cannot answer negative questions.

B is incorrect because it includes fractions.

D is incorrect because it lists the y values (what 20x is equal to) instead of the x values.