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Finding the Fourth Proportional to 1,289, 1,778.88 and 721.89

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Solution

The fourth proportional to 1,289, 1,778.88 and 721.89 is: 996.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289 : 1,778.88 = 721.89 : x
  2. Step 2: Convert to fraction form
    1,289/1,778.88 = 721.89/x
  3. Step 3: Cross multiply
    1,289x = 1,778.88 × 721.89
  4. Step 4: Simplify right side
    1,289x = 1,284,155.68
  5. Step 5: Solve for x
    x = 1,284,155.68/1,289
  6. Step 6: Final answer
    x = 996.24

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.