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Finding the Fourth Proportional to 758.60, 1,140.60 and 639.80

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Solution

The fourth proportional to 758.60, 1,140.60 and 639.80 is: 961.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    758.60 : 1,140.60 = 639.80 : x
  2. Step 2: Convert to fraction form
    758.60/1,140.60 = 639.80/x
  3. Step 3: Cross multiply
    758.60x = 1,140.60 × 639.80
  4. Step 4: Simplify right side
    758.60x = 729,755.88
  5. Step 5: Solve for x
    x = 729,755.88/758.60
  6. Step 6: Final answer
    x = 961.98

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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.