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Finding the Fourth Proportional to 120.18, 165.86 and 78.77

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Solution

The fourth proportional to 120.18, 165.86 and 78.77 is: 108.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.18 : 165.86 = 78.77 : x
  2. Step 2: Convert to fraction form
    120.18/165.86 = 78.77/x
  3. Step 3: Cross multiply
    120.18x = 165.86 × 78.77
  4. Step 4: Simplify right side
    120.18x = 13,063.86
  5. Step 5: Solve for x
    x = 13,063.86/120.18
  6. Step 6: Final answer
    x = 108.71

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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.