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Finding the Fourth Proportional to 561.60, 842.40 and 387.90

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Solution

The fourth proportional to 561.60, 842.40 and 387.90 is: 581.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    561.60 : 842.40 = 387.90 : x
  2. Step 2: Convert to fraction form
    561.60/842.40 = 387.90/x
  3. Step 3: Cross multiply
    561.60x = 842.40 × 387.90
  4. Step 4: Simplify right side
    561.60x = 326,766.96
  5. Step 5: Solve for x
    x = 326,766.96/561.60
  6. Step 6: Final answer
    x = 581.85

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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.