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Finding the Fourth Proportional to 391.39, 587.66 and 218.40

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Solution

The fourth proportional to 391.39, 587.66 and 218.40 is: 327.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.39 : 587.66 = 218.40 : x
  2. Step 2: Convert to fraction form
    391.39/587.66 = 218.40/x
  3. Step 3: Cross multiply
    391.39x = 587.66 × 218.40
  4. Step 4: Simplify right side
    391.39x = 128,343.49
  5. Step 5: Solve for x
    x = 128,343.49/391.39
  6. Step 6: Final answer
    x = 327.92

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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.