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Finding the Fourth Proportional to 120.31, 165.98 and 78.88

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Solution

The fourth proportional to 120.31, 165.98 and 78.88 is: 108.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.31 : 165.98 = 78.88 : x
  2. Step 2: Convert to fraction form
    120.31/165.98 = 78.88/x
  3. Step 3: Cross multiply
    120.31x = 165.98 × 78.88
  4. Step 4: Simplify right side
    120.31x = 13,092.11
  5. Step 5: Solve for x
    x = 13,092.11/120.31
  6. Step 6: Final answer
    x = 108.82

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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.