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Finding the Fourth Proportional to 981.12, 1,352.64 and 631.68

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Solution

The fourth proportional to 981.12, 1,352.64 and 631.68 is: 870.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.12 : 1,352.64 = 631.68 : x
  2. Step 2: Convert to fraction form
    981.12/1,352.64 = 631.68/x
  3. Step 3: Cross multiply
    981.12x = 1,352.64 × 631.68
  4. Step 4: Simplify right side
    981.12x = 854,435.64
  5. Step 5: Solve for x
    x = 854,435.64/981.12
  6. Step 6: Final answer
    x = 870.88

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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.