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Finding the Fourth Proportional to 821.10, 1,231.95 and 387.93

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Solution

The fourth proportional to 821.10, 1,231.95 and 387.93 is: 582.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.10 : 1,231.95 = 387.93 : x
  2. Step 2: Convert to fraction form
    821.10/1,231.95 = 387.93/x
  3. Step 3: Cross multiply
    821.10x = 1,231.95 × 387.93
  4. Step 4: Simplify right side
    821.10x = 477,910.36
  5. Step 5: Solve for x
    x = 477,910.36/821.10
  6. Step 6: Final answer
    x = 582.04

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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.