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Finding the Fourth Proportional to 981.09, 1,353.78 and 561.42

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Solution

The fourth proportional to 981.09, 1,353.78 and 561.42 is: 774.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.09 : 1,353.78 = 561.42 : x
  2. Step 2: Convert to fraction form
    981.09/1,353.78 = 561.42/x
  3. Step 3: Cross multiply
    981.09x = 1,353.78 × 561.42
  4. Step 4: Simplify right side
    981.09x = 760,039.17
  5. Step 5: Solve for x
    x = 760,039.17/981.09
  6. Step 6: Final answer
    x = 774.69

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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.