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Finding the Fourth Proportional to 878.21, 1,317.38 and 391.13

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Solution

The fourth proportional to 878.21, 1,317.38 and 391.13 is: 586.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.21 : 1,317.38 = 391.13 : x
  2. Step 2: Convert to fraction form
    878.21/1,317.38 = 391.13/x
  3. Step 3: Cross multiply
    878.21x = 1,317.38 × 391.13
  4. Step 4: Simplify right side
    878.21x = 515,258.30
  5. Step 5: Solve for x
    x = 515,258.30/878.21
  6. Step 6: Final answer
    x = 586.72

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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.