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Finding the Fourth Proportional to 878.78, 1,212.81 and 505.78

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Solution

The fourth proportional to 878.78, 1,212.81 and 505.78 is: 698.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.78 : 1,212.81 = 505.78 : x
  2. Step 2: Convert to fraction form
    878.78/1,212.81 = 505.78/x
  3. Step 3: Cross multiply
    878.78x = 1,212.81 × 505.78
  4. Step 4: Simplify right side
    878.78x = 613,410.11
  5. Step 5: Solve for x
    x = 613,410.11/878.78
  6. Step 6: Final answer
    x = 698.02

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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.