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Finding the Fourth Proportional to 861, 1,293 and 641.68

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Solution

The fourth proportional to 861, 1,293 and 641.68 is: 963.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    861 : 1,293 = 641.68 : x
  2. Step 2: Convert to fraction form
    861/1,293 = 641.68/x
  3. Step 3: Cross multiply
    861x = 1,293 × 641.68
  4. Step 4: Simplify right side
    861x = 829,692.24
  5. Step 5: Solve for x
    x = 829,692.24/861
  6. Step 6: Final answer
    x = 963.64

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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.