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Finding the Fourth Proportional to 102.20, 140.68 and 87.64

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Solution

The fourth proportional to 102.20, 140.68 and 87.64 is: 120.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.20 : 140.68 = 87.64 : x
  2. Step 2: Convert to fraction form
    102.20/140.68 = 87.64/x
  3. Step 3: Cross multiply
    102.20x = 140.68 × 87.64
  4. Step 4: Simplify right side
    102.20x = 12,329.20
  5. Step 5: Solve for x
    x = 12,329.20/102.20
  6. Step 6: Final answer
    x = 120.64

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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.