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Finding the Fourth Proportional to 138, 207.15 and 77.25

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Solution

The fourth proportional to 138, 207.15 and 77.25 is: 115.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    138 : 207.15 = 77.25 : x
  2. Step 2: Convert to fraction form
    138/207.15 = 77.25/x
  3. Step 3: Cross multiply
    138x = 207.15 × 77.25
  4. Step 4: Simplify right side
    138x = 16,002.34
  5. Step 5: Solve for x
    x = 16,002.34/138
  6. Step 6: Final answer
    x = 115.96

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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.