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Finding the Fourth Proportional to 981.45, 1,354.68 and 686.79

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Solution

The fourth proportional to 981.45, 1,354.68 and 686.79 is: 947.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.45 : 1,354.68 = 686.79 : x
  2. Step 2: Convert to fraction form
    981.45/1,354.68 = 686.79/x
  3. Step 3: Cross multiply
    981.45x = 1,354.68 × 686.79
  4. Step 4: Simplify right side
    981.45x = 930,380.68
  5. Step 5: Solve for x
    x = 930,380.68/981.45
  6. Step 6: Final answer
    x = 947.97

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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.