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Finding the Fourth Proportional to 756.40, 1,134.60 and 431.80

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Solution

The fourth proportional to 756.40, 1,134.60 and 431.80 is: 647.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    756.40 : 1,134.60 = 431.80 : x
  2. Step 2: Convert to fraction form
    756.40/1,134.60 = 431.80/x
  3. Step 3: Cross multiply
    756.40x = 1,134.60 × 431.80
  4. Step 4: Simplify right side
    756.40x = 489,920.28
  5. Step 5: Solve for x
    x = 489,920.28/756.40
  6. Step 6: Final answer
    x = 647.70

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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.