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Finding the Fourth Proportional to 921.90, 1,384.20 and 557.40

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Solution

The fourth proportional to 921.90, 1,384.20 and 557.40 is: 836.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.90 : 1,384.20 = 557.40 : x
  2. Step 2: Convert to fraction form
    921.90/1,384.20 = 557.40/x
  3. Step 3: Cross multiply
    921.90x = 1,384.20 × 557.40
  4. Step 4: Simplify right side
    921.90x = 771,553.08
  5. Step 5: Solve for x
    x = 771,553.08/921.90
  6. Step 6: Final answer
    x = 836.92

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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.