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Finding the Fourth Proportional to 861.08, 1,291.56 and 313.20

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Solution

The fourth proportional to 861.08, 1,291.56 and 313.20 is: 469.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.08 : 1,291.56 = 313.20 : x
  2. Step 2: Convert to fraction form
    861.08/1,291.56 = 313.20/x
  3. Step 3: Cross multiply
    861.08x = 1,291.56 × 313.20
  4. Step 4: Simplify right side
    861.08x = 404,516.59
  5. Step 5: Solve for x
    x = 404,516.59/861.08
  6. Step 6: Final answer
    x = 469.78

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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.