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Finding the Fourth Proportional to 981.90, 1,355.49 and 688.71

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Solution

The fourth proportional to 981.90, 1,355.49 and 688.71 is: 950.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.90 : 1,355.49 = 688.71 : x
  2. Step 2: Convert to fraction form
    981.90/1,355.49 = 688.71/x
  3. Step 3: Cross multiply
    981.90x = 1,355.49 × 688.71
  4. Step 4: Simplify right side
    981.90x = 933,539.52
  5. Step 5: Solve for x
    x = 933,539.52/981.90
  6. Step 6: Final answer
    x = 950.75

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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.