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Finding the Fourth Proportional to 865.80, 1,195.20 and 689.40

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Solution

The fourth proportional to 865.80, 1,195.20 and 689.40 is: 951.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.80 : 1,195.20 = 689.40 : x
  2. Step 2: Convert to fraction form
    865.80/1,195.20 = 689.40/x
  3. Step 3: Cross multiply
    865.80x = 1,195.20 × 689.40
  4. Step 4: Simplify right side
    865.80x = 823,970.88
  5. Step 5: Solve for x
    x = 823,970.88/865.80
  6. Step 6: Final answer
    x = 951.69

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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.