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Finding the Fourth Proportional to 861.76, 1,291.56 and 427.96

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Solution

The fourth proportional to 861.76, 1,291.56 and 427.96 is: 641.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.76 : 1,291.56 = 427.96 : x
  2. Step 2: Convert to fraction form
    861.76/1,291.56 = 427.96/x
  3. Step 3: Cross multiply
    861.76x = 1,291.56 × 427.96
  4. Step 4: Simplify right side
    861.76x = 552,736.02
  5. Step 5: Solve for x
    x = 552,736.02/861.76
  6. Step 6: Final answer
    x = 641.40

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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.