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Finding the Fourth Proportional to 878.12, 1,211.78 and 485.15

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Solution

The fourth proportional to 878.12, 1,211.78 and 485.15 is: 669.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.12 : 1,211.78 = 485.15 : x
  2. Step 2: Convert to fraction form
    878.12/1,211.78 = 485.15/x
  3. Step 3: Cross multiply
    878.12x = 1,211.78 × 485.15
  4. Step 4: Simplify right side
    878.12x = 587,890.22
  5. Step 5: Solve for x
    x = 587,890.22/878.12
  6. Step 6: Final answer
    x = 669.49

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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.