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Finding the Fourth Proportional to 821.10, 1,230.84 and 387.75

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Solution

The fourth proportional to 821.10, 1,230.84 and 387.75 is: 581.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.10 : 1,230.84 = 387.75 : x
  2. Step 2: Convert to fraction form
    821.10/1,230.84 = 387.75/x
  3. Step 3: Cross multiply
    821.10x = 1,230.84 × 387.75
  4. Step 4: Simplify right side
    821.10x = 477,258.21
  5. Step 5: Solve for x
    x = 477,258.21/821.10
  6. Step 6: Final answer
    x = 581.24

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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.