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Finding the Fourth Proportional to 861.38, 1,292.56 and 428.54

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Solution

The fourth proportional to 861.38, 1,292.56 and 428.54 is: 643.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.38 : 1,292.56 = 428.54 : x
  2. Step 2: Convert to fraction form
    861.38/1,292.56 = 428.54/x
  3. Step 3: Cross multiply
    861.38x = 1,292.56 × 428.54
  4. Step 4: Simplify right side
    861.38x = 553,913.66
  5. Step 5: Solve for x
    x = 553,913.66/861.38
  6. Step 6: Final answer
    x = 643.05

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Double scale
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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.