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Finding the Fourth Proportional to 840.69, 1,259.88 and 428.96

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Solution

The fourth proportional to 840.69, 1,259.88 and 428.96 is: 642.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.69 : 1,259.88 = 428.96 : x
  2. Step 2: Convert to fraction form
    840.69/1,259.88 = 428.96/x
  3. Step 3: Cross multiply
    840.69x = 1,259.88 × 428.96
  4. Step 4: Simplify right side
    840.69x = 540,439.72
  5. Step 5: Solve for x
    x = 540,439.72/840.69
  6. Step 6: Final answer
    x = 642.85

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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.