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Finding the Fourth Proportional to 120.85, 166.74 and 78.82

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Solution

The fourth proportional to 120.85, 166.74 and 78.82 is: 108.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.85 : 166.74 = 78.82 : x
  2. Step 2: Convert to fraction form
    120.85/166.74 = 78.82/x
  3. Step 3: Cross multiply
    120.85x = 166.74 × 78.82
  4. Step 4: Simplify right side
    120.85x = 13,142.45
  5. Step 5: Solve for x
    x = 13,142.45/120.85
  6. Step 6: Final answer
    x = 108.75

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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.