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Finding the Fourth Proportional to 861.72, 1,291.56 and 313.49

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Solution

The fourth proportional to 861.72, 1,291.56 and 313.49 is: 469.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.72 : 1,291.56 = 313.49 : x
  2. Step 2: Convert to fraction form
    861.72/1,291.56 = 313.49/x
  3. Step 3: Cross multiply
    861.72x = 1,291.56 × 313.49
  4. Step 4: Simplify right side
    861.72x = 404,884.69
  5. Step 5: Solve for x
    x = 404,884.69/861.72
  6. Step 6: Final answer
    x = 469.86

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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.