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Finding the Fourth Proportional to 861.45, 1,186.70 and 686.49

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Solution

The fourth proportional to 861.45, 1,186.70 and 686.49 is: 945.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.45 : 1,186.70 = 686.49 : x
  2. Step 2: Convert to fraction form
    861.45/1,186.70 = 686.49/x
  3. Step 3: Cross multiply
    861.45x = 1,186.70 × 686.49
  4. Step 4: Simplify right side
    861.45x = 814,654.25
  5. Step 5: Solve for x
    x = 814,654.25/861.45
  6. Step 6: Final answer
    x = 945.68

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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.