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Finding the Fourth Proportional to 147.20, 220.90 and 85.64

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Solution

The fourth proportional to 147.20, 220.90 and 85.64 is: 128.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    147.20 : 220.90 = 85.64 : x
  2. Step 2: Convert to fraction form
    147.20/220.90 = 85.64/x
  3. Step 3: Cross multiply
    147.20x = 220.90 × 85.64
  4. Step 4: Simplify right side
    147.20x = 18,917.88
  5. Step 5: Solve for x
    x = 18,917.88/147.20
  6. Step 6: Final answer
    x = 128.52

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.