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Finding the Fourth Proportional to 138.20, 207.32 and 42

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Solution

The fourth proportional to 138.20, 207.32 and 42 is: 63.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.20 : 207.32 = 42 : x
  2. Step 2: Convert to fraction form
    138.20/207.32 = 42/x
  3. Step 3: Cross multiply
    138.20x = 207.32 × 42
  4. Step 4: Simplify right side
    138.20x = 8,707.23
  5. Step 5: Solve for x
    x = 8,707.23/138.20
  6. Step 6: Final answer
    x = 63.01

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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.