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Finding the Fourth Proportional to 878.22, 1,317.12 and 391

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Solution

The fourth proportional to 878.22, 1,317.12 and 391 is: 586.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.22 : 1,317.12 = 391 : x
  2. Step 2: Convert to fraction form
    878.22/1,317.12 = 391/x
  3. Step 3: Cross multiply
    878.22x = 1,317.12 × 391
  4. Step 4: Simplify right side
    878.22x = 514,993.92
  5. Step 5: Solve for x
    x = 514,993.92/878.22
  6. Step 6: Final answer
    x = 586.41

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.