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Finding the Fourth Proportional to 709.20, 978.48 and 398.64

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Solution

The fourth proportional to 709.20, 978.48 and 398.64 is: 550.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.20 : 978.48 = 398.64 : x
  2. Step 2: Convert to fraction form
    709.20/978.48 = 398.64/x
  3. Step 3: Cross multiply
    709.20x = 978.48 × 398.64
  4. Step 4: Simplify right side
    709.20x = 390,061.27
  5. Step 5: Solve for x
    x = 390,061.27/709.20
  6. Step 6: Final answer
    x = 550.00

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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.