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Finding the Fourth Proportional to 820.42, 1,230.30 and 387.28

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Solution

The fourth proportional to 820.42, 1,230.30 and 387.28 is: 580.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.42 : 1,230.30 = 387.28 : x
  2. Step 2: Convert to fraction form
    820.42/1,230.30 = 387.28/x
  3. Step 3: Cross multiply
    820.42x = 1,230.30 × 387.28
  4. Step 4: Simplify right side
    820.42x = 476,470.58
  5. Step 5: Solve for x
    x = 476,470.58/820.42
  6. Step 6: Final answer
    x = 580.76

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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.