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Finding the Fourth Proportional to 120.86, 166.87 and 100.21

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Solution

The fourth proportional to 120.86, 166.87 and 100.21 is: 138.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.86 : 166.87 = 100.21 : x
  2. Step 2: Convert to fraction form
    120.86/166.87 = 100.21/x
  3. Step 3: Cross multiply
    120.86x = 166.87 × 100.21
  4. Step 4: Simplify right side
    120.86x = 16,722.04
  5. Step 5: Solve for x
    x = 16,722.04/120.86
  6. Step 6: Final answer
    x = 138.36

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.