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Finding the Fourth Proportional to 398.79, 598.17 and 138.79

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Solution

The fourth proportional to 398.79, 598.17 and 138.79 is: 208.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    398.79 : 598.17 = 138.79 : x
  2. Step 2: Convert to fraction form
    398.79/598.17 = 138.79/x
  3. Step 3: Cross multiply
    398.79x = 598.17 × 138.79
  4. Step 4: Simplify right side
    398.79x = 83,018.44
  5. Step 5: Solve for x
    x = 83,018.44/398.79
  6. Step 6: Final answer
    x = 208.18

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.