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Finding the Fourth Proportional to 187.78, 258.97 and 138.78

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Solution

The fourth proportional to 187.78, 258.97 and 138.78 is: 191.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    187.78 : 258.97 = 138.78 : x
  2. Step 2: Convert to fraction form
    187.78/258.97 = 138.78/x
  3. Step 3: Cross multiply
    187.78x = 258.97 × 138.78
  4. Step 4: Simplify right side
    187.78x = 35,939.86
  5. Step 5: Solve for x
    x = 35,939.86/187.78
  6. Step 6: Final answer
    x = 191.39

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.