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Finding the Fourth Proportional to 840.40, 1,257.90 and 656.80

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Solution

The fourth proportional to 840.40, 1,257.90 and 656.80 is: 983.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.40 : 1,257.90 = 656.80 : x
  2. Step 2: Convert to fraction form
    840.40/1,257.90 = 656.80/x
  3. Step 3: Cross multiply
    840.40x = 1,257.90 × 656.80
  4. Step 4: Simplify right side
    840.40x = 826,188.72
  5. Step 5: Solve for x
    x = 826,188.72/840.40
  6. Step 6: Final answer
    x = 983.09

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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.