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Finding the Fourth Proportional to 138.64, 207.68 and 128.64

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Solution

The fourth proportional to 138.64, 207.68 and 128.64 is: 192.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.64 : 207.68 = 128.64 : x
  2. Step 2: Convert to fraction form
    138.64/207.68 = 128.64/x
  3. Step 3: Cross multiply
    138.64x = 207.68 × 128.64
  4. Step 4: Simplify right side
    138.64x = 26,715.96
  5. Step 5: Solve for x
    x = 26,715.96/138.64
  6. Step 6: Final answer
    x = 192.70

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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.