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Finding the Fourth Proportional to 878.38, 1,212.15 and 485.42

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Solution

The fourth proportional to 878.38, 1,212.15 and 485.42 is: 669.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.38 : 1,212.15 = 485.42 : x
  2. Step 2: Convert to fraction form
    878.38/1,212.15 = 485.42/x
  3. Step 3: Cross multiply
    878.38x = 1,212.15 × 485.42
  4. Step 4: Simplify right side
    878.38x = 588,401.85
  5. Step 5: Solve for x
    x = 588,401.85/878.38
  6. Step 6: Final answer
    x = 669.87

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1.5x scale

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.