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Finding the Fourth Proportional to 709.28, 978.78 and 398.76

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Solution

The fourth proportional to 709.28, 978.78 and 398.76 is: 550.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.28 : 978.78 = 398.76 : x
  2. Step 2: Convert to fraction form
    709.28/978.78 = 398.76/x
  3. Step 3: Cross multiply
    709.28x = 978.78 × 398.76
  4. Step 4: Simplify right side
    709.28x = 390,298.31
  5. Step 5: Solve for x
    x = 390,298.31/709.28
  6. Step 6: Final answer
    x = 550.27

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1.5x scale

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.