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Finding the Fourth Proportional to 390.78, 585.36 and 198

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Solution

The fourth proportional to 390.78, 585.36 and 198 is: 296.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.78 : 585.36 = 198 : x
  2. Step 2: Convert to fraction form
    390.78/585.36 = 198/x
  3. Step 3: Cross multiply
    390.78x = 585.36 × 198
  4. Step 4: Simplify right side
    390.78x = 115,901.28
  5. Step 5: Solve for x
    x = 115,901.28/390.78
  6. Step 6: Final answer
    x = 296.59

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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.