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Finding the Fourth Proportional to 939.21, 1,409.13 and 391.65

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Solution

The fourth proportional to 939.21, 1,409.13 and 391.65 is: 587.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.21 : 1,409.13 = 391.65 : x
  2. Step 2: Convert to fraction form
    939.21/1,409.13 = 391.65/x
  3. Step 3: Cross multiply
    939.21x = 1,409.13 × 391.65
  4. Step 4: Simplify right side
    939.21x = 551,885.76
  5. Step 5: Solve for x
    x = 551,885.76/939.21
  6. Step 6: Final answer
    x = 587.61

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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.