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Finding the Fourth Proportional to 939, 1,409.12 and 391.18

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Solution

The fourth proportional to 939, 1,409.12 and 391.18 is: 587.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    939 : 1,409.12 = 391.18 : x
  2. Step 2: Convert to fraction form
    939/1,409.12 = 391.18/x
  3. Step 3: Cross multiply
    939x = 1,409.12 × 391.18
  4. Step 4: Simplify right side
    939x = 551,219.56
  5. Step 5: Solve for x
    x = 551,219.56/939
  6. Step 6: Final answer
    x = 587.03

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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.