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Finding the Fourth Proportional to 709.70, 979.35 and 399.20

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Solution

The fourth proportional to 709.70, 979.35 and 399.20 is: 550.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.70 : 979.35 = 399.20 : x
  2. Step 2: Convert to fraction form
    709.70/979.35 = 399.20/x
  3. Step 3: Cross multiply
    709.70x = 979.35 × 399.20
  4. Step 4: Simplify right side
    709.70x = 390,956.52
  5. Step 5: Solve for x
    x = 390,956.52/709.70
  6. Step 6: Final answer
    x = 550.88

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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.