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Finding the Fourth Proportional to 769.80, 1,154.70 and 721.80

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Solution

The fourth proportional to 769.80, 1,154.70 and 721.80 is: 1,082.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    769.80 : 1,154.70 = 721.80 : x
  2. Step 2: Convert to fraction form
    769.80/1,154.70 = 721.80/x
  3. Step 3: Cross multiply
    769.80x = 1,154.70 × 721.80
  4. Step 4: Simplify right side
    769.80x = 833,462.46
  5. Step 5: Solve for x
    x = 833,462.46/769.80
  6. Step 6: Final answer
    x = 1,082.70

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.