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Finding the Fourth Proportional to 939.50, 1,408.80 and 391.58

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Solution

The fourth proportional to 939.50, 1,408.80 and 391.58 is: 587.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.50 : 1,408.80 = 391.58 : x
  2. Step 2: Convert to fraction form
    939.50/1,408.80 = 391.58/x
  3. Step 3: Cross multiply
    939.50x = 1,408.80 × 391.58
  4. Step 4: Simplify right side
    939.50x = 551,657.90
  5. Step 5: Solve for x
    x = 551,657.90/939.50
  6. Step 6: Final answer
    x = 587.18

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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.