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Finding the Fourth Proportional to 120.38, 166.01 and 78.90

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Solution

The fourth proportional to 120.38, 166.01 and 78.90 is: 108.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.38 : 166.01 = 78.90 : x
  2. Step 2: Convert to fraction form
    120.38/166.01 = 78.90/x
  3. Step 3: Cross multiply
    120.38x = 166.01 × 78.90
  4. Step 4: Simplify right side
    120.38x = 13,097.79
  5. Step 5: Solve for x
    x = 13,097.79/120.38
  6. Step 6: Final answer
    x = 108.81

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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.