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Finding the Fourth Proportional to 939.76, 1,409.91 and 391.66

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Solution

The fourth proportional to 939.76, 1,409.91 and 391.66 is: 587.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.76 : 1,409.91 = 391.66 : x
  2. Step 2: Convert to fraction form
    939.76/1,409.91 = 391.66/x
  3. Step 3: Cross multiply
    939.76x = 1,409.91 × 391.66
  4. Step 4: Simplify right side
    939.76x = 552,205.35
  5. Step 5: Solve for x
    x = 552,205.35/939.76
  6. Step 6: Final answer
    x = 587.60

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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.