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Finding the Fourth Proportional to 840.61, 1,261.23 and 429.85

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Solution

The fourth proportional to 840.61, 1,261.23 and 429.85 is: 644.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.61 : 1,261.23 = 429.85 : x
  2. Step 2: Convert to fraction form
    840.61/1,261.23 = 429.85/x
  3. Step 3: Cross multiply
    840.61x = 1,261.23 × 429.85
  4. Step 4: Simplify right side
    840.61x = 542,139.72
  5. Step 5: Solve for x
    x = 542,139.72/840.61
  6. Step 6: Final answer
    x = 644.94

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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.