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Finding the Fourth Proportional to 939.75, 1,409.39 and 391.63

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Solution

The fourth proportional to 939.75, 1,409.39 and 391.63 is: 587.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.75 : 1,409.39 = 391.63 : x
  2. Step 2: Convert to fraction form
    939.75/1,409.39 = 391.63/x
  3. Step 3: Cross multiply
    939.75x = 1,409.39 × 391.63
  4. Step 4: Simplify right side
    939.75x = 551,962.15
  5. Step 5: Solve for x
    x = 551,962.15/939.75
  6. Step 6: Final answer
    x = 587.35

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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.