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Finding the Fourth Proportional to 218.86, 328.32 and 81.87

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Solution

The fourth proportional to 218.86, 328.32 and 81.87 is: 122.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    218.86 : 328.32 = 81.87 : x
  2. Step 2: Convert to fraction form
    218.86/328.32 = 81.87/x
  3. Step 3: Cross multiply
    218.86x = 328.32 × 81.87
  4. Step 4: Simplify right side
    218.86x = 26,879.56
  5. Step 5: Solve for x
    x = 26,879.56/218.86
  6. Step 6: Final answer
    x = 122.82

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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.