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Finding the Fourth Proportional to 981.25, 1,353.75 and 686.91

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Solution

The fourth proportional to 981.25, 1,353.75 and 686.91 is: 947.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.25 : 1,353.75 = 686.91 : x
  2. Step 2: Convert to fraction form
    981.25/1,353.75 = 686.91/x
  3. Step 3: Cross multiply
    981.25x = 1,353.75 × 686.91
  4. Step 4: Simplify right side
    981.25x = 929,906.91
  5. Step 5: Solve for x
    x = 929,906.91/981.25
  6. Step 6: Final answer
    x = 947.68

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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.