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Finding the Fourth Proportional to 138.42, 206.78 and 135.72

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Solution

The fourth proportional to 138.42, 206.78 and 135.72 is: 202.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.42 : 206.78 = 135.72 : x
  2. Step 2: Convert to fraction form
    138.42/206.78 = 135.72/x
  3. Step 3: Cross multiply
    138.42x = 206.78 × 135.72
  4. Step 4: Simplify right side
    138.42x = 28,063.50
  5. Step 5: Solve for x
    x = 28,063.50/138.42
  6. Step 6: Final answer
    x = 202.74

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.