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Finding the Fourth Proportional to 709.25, 978.80 and 398.75

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Solution

The fourth proportional to 709.25, 978.80 and 398.75 is: 550.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.25 : 978.80 = 398.75 : x
  2. Step 2: Convert to fraction form
    709.25/978.80 = 398.75/x
  3. Step 3: Cross multiply
    709.25x = 978.80 × 398.75
  4. Step 4: Simplify right side
    709.25x = 390,296.50
  5. Step 5: Solve for x
    x = 390,296.50/709.25
  6. Step 6: Final answer
    x = 550.29

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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.