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Finding the Fourth Proportional to 427, 640.64 and 138.45

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Solution

The fourth proportional to 427, 640.64 and 138.45 is: 207.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    427 : 640.64 = 138.45 : x
  2. Step 2: Convert to fraction form
    427/640.64 = 138.45/x
  3. Step 3: Cross multiply
    427x = 640.64 × 138.45
  4. Step 4: Simplify right side
    427x = 88,696.61
  5. Step 5: Solve for x
    x = 88,696.61/427
  6. Step 6: Final answer
    x = 207.72

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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.