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Finding the Fourth Proportional to 821.30, 1,230.89 and 430.31

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Solution

The fourth proportional to 821.30, 1,230.89 and 430.31 is: 644.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.30 : 1,230.89 = 430.31 : x
  2. Step 2: Convert to fraction form
    821.30/1,230.89 = 430.31/x
  3. Step 3: Cross multiply
    821.30x = 1,230.89 × 430.31
  4. Step 4: Simplify right side
    821.30x = 529,667.28
  5. Step 5: Solve for x
    x = 529,667.28/821.30
  6. Step 6: Final answer
    x = 644.91

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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.