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Finding the Fourth Proportional to 138.42, 207.63 and 74.28

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Solution

The fourth proportional to 138.42, 207.63 and 74.28 is: 111.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.42 : 207.63 = 74.28 : x
  2. Step 2: Convert to fraction form
    138.42/207.63 = 74.28/x
  3. Step 3: Cross multiply
    138.42x = 207.63 × 74.28
  4. Step 4: Simplify right side
    138.42x = 15,422.76
  5. Step 5: Solve for x
    x = 15,422.76/138.42
  6. Step 6: Final answer
    x = 111.42

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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.