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Finding the Fourth Proportional to 709.19, 978.68 and 398.69

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Solution

The fourth proportional to 709.19, 978.68 and 398.69 is: 550.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.19 : 978.68 = 398.69 : x
  2. Step 2: Convert to fraction form
    709.19/978.68 = 398.69/x
  3. Step 3: Cross multiply
    709.19x = 978.68 × 398.69
  4. Step 4: Simplify right side
    709.19x = 390,186.98
  5. Step 5: Solve for x
    x = 390,186.98/709.19
  6. Step 6: Final answer
    x = 550.19

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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.