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Finding the Fourth Proportional to 981.20, 1,353.99 and 561.50

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Solution

The fourth proportional to 981.20, 1,353.99 and 561.50 is: 774.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.20 : 1,353.99 = 561.50 : x
  2. Step 2: Convert to fraction form
    981.20/1,353.99 = 561.50/x
  3. Step 3: Cross multiply
    981.20x = 1,353.99 × 561.50
  4. Step 4: Simplify right side
    981.20x = 760,265.39
  5. Step 5: Solve for x
    x = 760,265.39/981.20
  6. Step 6: Final answer
    x = 774.83

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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.