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Finding the Fourth Proportional to 138.60, 207.84 and 90.36

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Solution

The fourth proportional to 138.60, 207.84 and 90.36 is: 135.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.60 : 207.84 = 90.36 : x
  2. Step 2: Convert to fraction form
    138.60/207.84 = 90.36/x
  3. Step 3: Cross multiply
    138.60x = 207.84 × 90.36
  4. Step 4: Simplify right side
    138.60x = 18,780.42
  5. Step 5: Solve for x
    x = 18,780.42/138.60
  6. Step 6: Final answer
    x = 135.50

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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.