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Finding the Fourth Proportional to 981.20, 1,354.20 and 645.41

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Solution

The fourth proportional to 981.20, 1,354.20 and 645.41 is: 890.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.20 : 1,354.20 = 645.41 : x
  2. Step 2: Convert to fraction form
    981.20/1,354.20 = 645.41/x
  3. Step 3: Cross multiply
    981.20x = 1,354.20 × 645.41
  4. Step 4: Simplify right side
    981.20x = 874,014.22
  5. Step 5: Solve for x
    x = 874,014.22/981.20
  6. Step 6: Final answer
    x = 890.76

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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.