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Finding the Fourth Proportional to 120.20, 165.78 and 91.16

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Solution

The fourth proportional to 120.20, 165.78 and 91.16 is: 125.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.20 : 165.78 = 91.16 : x
  2. Step 2: Convert to fraction form
    120.20/165.78 = 91.16/x
  3. Step 3: Cross multiply
    120.20x = 165.78 × 91.16
  4. Step 4: Simplify right side
    120.20x = 15,112.50
  5. Step 5: Solve for x
    x = 15,112.50/120.20
  6. Step 6: Final answer
    x = 125.73

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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.