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Finding the Fourth Proportional to 778.80, 1,167.40 and 431.60

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Solution

The fourth proportional to 778.80, 1,167.40 and 431.60 is: 646.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    778.80 : 1,167.40 = 431.60 : x
  2. Step 2: Convert to fraction form
    778.80/1,167.40 = 431.60/x
  3. Step 3: Cross multiply
    778.80x = 1,167.40 × 431.60
  4. Step 4: Simplify right side
    778.80x = 503,849.84
  5. Step 5: Solve for x
    x = 503,849.84/778.80
  6. Step 6: Final answer
    x = 646.96

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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.