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Finding the Fourth Proportional to 709.12, 978.36 and 398.56

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Solution

The fourth proportional to 709.12, 978.36 and 398.56 is: 549.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.12 : 978.36 = 398.56 : x
  2. Step 2: Convert to fraction form
    709.12/978.36 = 398.56/x
  3. Step 3: Cross multiply
    709.12x = 978.36 × 398.56
  4. Step 4: Simplify right side
    709.12x = 389,935.16
  5. Step 5: Solve for x
    x = 389,935.16/709.12
  6. Step 6: Final answer
    x = 549.89

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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.