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Finding the Fourth Proportional to 821.64, 1,230.19 and 455.78

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Solution

The fourth proportional to 821.64, 1,230.19 and 455.78 is: 682.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.64 : 1,230.19 = 455.78 : x
  2. Step 2: Convert to fraction form
    821.64/1,230.19 = 455.78/x
  3. Step 3: Cross multiply
    821.64x = 1,230.19 × 455.78
  4. Step 4: Simplify right side
    821.64x = 560,691.01
  5. Step 5: Solve for x
    x = 560,691.01/821.64
  6. Step 6: Final answer
    x = 682.40

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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.