Math Problem Statement

Which of the following tables represents a direct proportion?

Solution

To determine which table represents a direct proportion, we need to check if there is a consistent ratio between the values of xx and yy in each table.

A relationship is a direct proportion if y=kxy = kx, where kk (the constant of proportionality) remains the same for each pair of xx and yy.

Analyzing Each Table:

  1. Table A:

    • Ratios: yx=25,410,615,820\frac{y}{x} = \frac{2}{5}, \frac{4}{10}, \frac{6}{15}, \frac{8}{20}.
    • All ratios are 25\frac{2}{5}, which is constant. Therefore, Table A shows direct proportion.
  2. Table B:

    • Ratios: yx=21,52,73,84\frac{y}{x} = \frac{2}{1}, \frac{5}{2}, \frac{7}{3}, \frac{8}{4}.
    • Ratios are not consistent. Thus, Table B does not represent direct proportion.
  3. Table C:

    • Ratios: yx=12,34,56,78\frac{y}{x} = \frac{1}{2}, \frac{3}{4}, \frac{5}{6}, \frac{7}{8}.
    • Ratios are not consistent. Thus, Table C does not represent direct proportion.
  4. Table D:

    • Ratios: yx=42,84,126,168\frac{y}{x} = \frac{4}{2}, \frac{8}{4}, \frac{12}{6}, \frac{16}{8}.
    • All ratios are 22, which is constant. Therefore, Table D shows direct proportion.

Conclusion:

Both Table A and Table D represent direct proportion, but since the question is asking for a single answer, if only one choice can be made, you would generally select Table A (as it is likely meant to be the primary answer in multiple-choice settings).

Would you like more details on this analysis or have any questions?


Further Questions:

  1. What is the constant of proportionality for each table?
  2. How can you identify inverse proportion in similar tables?
  3. Why does a constant ratio confirm direct proportion?
  4. Can we graph these tables to visualize direct proportion?
  5. How would the values change if these tables represented inverse proportions?

Tip:

When checking for direct proportion, calculating the ratio yx\frac{y}{x} for each pair helps confirm if it remains constant.

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Math Problem Analysis

Mathematical Concepts

Direct Proportion
Ratio

Formulas

y = kx (Direct Proportion Formula)
Ratio: y / x = constant

Theorems

Constant Ratio Theorem for Direct Proportion

Suitable Grade Level

Grades 6-8