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Finding the Fourth Proportional to 819.70, 1,229.55 and 690.10

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Solution

The fourth proportional to 819.70, 1,229.55 and 690.10 is: 1,035.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.70 : 1,229.55 = 690.10 : x
  2. Step 2: Convert to fraction form
    819.70/1,229.55 = 690.10/x
  3. Step 3: Cross multiply
    819.70x = 1,229.55 × 690.10
  4. Step 4: Simplify right side
    819.70x = 848,512.46
  5. Step 5: Solve for x
    x = 848,512.46/819.70
  6. Step 6: Final answer
    x = 1,035.15

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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.