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Finding the Fourth Proportional to 391.78, 587.70 and 117.87

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Solution

The fourth proportional to 391.78, 587.70 and 117.87 is: 176.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.78 : 587.70 = 117.87 : x
  2. Step 2: Convert to fraction form
    391.78/587.70 = 117.87/x
  3. Step 3: Cross multiply
    391.78x = 587.70 × 117.87
  4. Step 4: Simplify right side
    391.78x = 69,272.20
  5. Step 5: Solve for x
    x = 69,272.20/391.78
  6. Step 6: Final answer
    x = 176.81

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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.