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Finding the Fourth Proportional to 820.72, 1,230.50 and 387.64

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Solution

The fourth proportional to 820.72, 1,230.50 and 387.64 is: 581.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.72 : 1,230.50 = 387.64 : x
  2. Step 2: Convert to fraction form
    820.72/1,230.50 = 387.64/x
  3. Step 3: Cross multiply
    820.72x = 1,230.50 × 387.64
  4. Step 4: Simplify right side
    820.72x = 476,991.02
  5. Step 5: Solve for x
    x = 476,991.02/820.72
  6. Step 6: Final answer
    x = 581.19

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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.