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Finding the Fourth Proportional to 12.39, 18.57 and 7.87

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Solution

The fourth proportional to 12.39, 18.57 and 7.87 is: 11.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    12.39 : 18.57 = 7.87 : x
  2. Step 2: Convert to fraction form
    12.39/18.57 = 7.87/x
  3. Step 3: Cross multiply
    12.39x = 18.57 × 7.87
  4. Step 4: Simplify right side
    12.39x = 146.11
  5. Step 5: Solve for x
    x = 146.11/12.39
  6. Step 6: Final answer
    x = 11.80

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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.