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Finding the Fourth Proportional to 980.18, 1,351.86 and 861.90

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Solution

The fourth proportional to 980.18, 1,351.86 and 861.90 is: 1,188.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    980.18 : 1,351.86 = 861.90 : x
  2. Step 2: Convert to fraction form
    980.18/1,351.86 = 861.90/x
  3. Step 3: Cross multiply
    980.18x = 1,351.86 × 861.90
  4. Step 4: Simplify right side
    980.18x = 1,165,168.13
  5. Step 5: Solve for x
    x = 1,165,168.13/980.18
  6. Step 6: Final answer
    x = 1,188.73

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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.