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Finding the Fourth Proportional to 878.30, 1,212 and 485.31

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Solution

The fourth proportional to 878.30, 1,212 and 485.31 is: 669.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.30 : 1,212 = 485.31 : x
  2. Step 2: Convert to fraction form
    878.30/1,212 = 485.31/x
  3. Step 3: Cross multiply
    878.30x = 1,212 × 485.31
  4. Step 4: Simplify right side
    878.30x = 588,195.72
  5. Step 5: Solve for x
    x = 588,195.72/878.30
  6. Step 6: Final answer
    x = 669.70

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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.