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Finding the Fourth Proportional to 861.91, 1,291.72 and 313.56

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Solution

The fourth proportional to 861.91, 1,291.72 and 313.56 is: 469.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.91 : 1,291.72 = 313.56 : x
  2. Step 2: Convert to fraction form
    861.91/1,291.72 = 313.56/x
  3. Step 3: Cross multiply
    861.91x = 1,291.72 × 313.56
  4. Step 4: Simplify right side
    861.91x = 405,030.16
  5. Step 5: Solve for x
    x = 405,030.16/861.91
  6. Step 6: Final answer
    x = 469.92

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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.