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Finding the Fourth Proportional to 861.20, 1,188.36 and 686.48

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Solution

The fourth proportional to 861.20, 1,188.36 and 686.48 is: 947.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.20 : 1,188.36 = 686.48 : x
  2. Step 2: Convert to fraction form
    861.20/1,188.36 = 686.48/x
  3. Step 3: Cross multiply
    861.20x = 1,188.36 × 686.48
  4. Step 4: Simplify right side
    861.20x = 815,785.37
  5. Step 5: Solve for x
    x = 815,785.37/861.20
  6. Step 6: Final answer
    x = 947.27

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.