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Finding the Fourth Proportional to 981.12, 1,353.68 and 631.92

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Solution

The fourth proportional to 981.12, 1,353.68 and 631.92 is: 871.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.12 : 1,353.68 = 631.92 : x
  2. Step 2: Convert to fraction form
    981.12/1,353.68 = 631.92/x
  3. Step 3: Cross multiply
    981.12x = 1,353.68 × 631.92
  4. Step 4: Simplify right side
    981.12x = 855,417.47
  5. Step 5: Solve for x
    x = 855,417.47/981.12
  6. Step 6: Final answer
    x = 871.88

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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.