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Finding the Fourth Proportional to 878.72, 1,212.57 and 505.78

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Solution

The fourth proportional to 878.72, 1,212.57 and 505.78 is: 697.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.72 : 1,212.57 = 505.78 : x
  2. Step 2: Convert to fraction form
    878.72/1,212.57 = 505.78/x
  3. Step 3: Cross multiply
    878.72x = 1,212.57 × 505.78
  4. Step 4: Simplify right side
    878.72x = 613,290.62
  5. Step 5: Solve for x
    x = 613,290.62/878.72
  6. Step 6: Final answer
    x = 697.94

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.