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Finding the Fourth Proportional to 878.32, 1,317.78 and 391.72

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Solution

The fourth proportional to 878.32, 1,317.78 and 391.72 is: 587.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.32 : 1,317.78 = 391.72 : x
  2. Step 2: Convert to fraction form
    878.32/1,317.78 = 391.72/x
  3. Step 3: Cross multiply
    878.32x = 1,317.78 × 391.72
  4. Step 4: Simplify right side
    878.32x = 516,200.78
  5. Step 5: Solve for x
    x = 516,200.78/878.32
  6. Step 6: Final answer
    x = 587.71

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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.