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Finding the Fourth Proportional to 861.38, 1,291.68 and 313.46

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Solution

The fourth proportional to 861.38, 1,291.68 and 313.46 is: 470.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.38 : 1,291.68 = 313.46 : x
  2. Step 2: Convert to fraction form
    861.38/1,291.68 = 313.46/x
  3. Step 3: Cross multiply
    861.38x = 1,291.68 × 313.46
  4. Step 4: Simplify right side
    861.38x = 404,890.01
  5. Step 5: Solve for x
    x = 404,890.01/861.38
  6. Step 6: Final answer
    x = 470.05

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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.