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Finding the Fourth Proportional to 18.78, 25.90 and 11.86

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Solution

The fourth proportional to 18.78, 25.90 and 11.86 is: 16.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.78 : 25.90 = 11.86 : x
  2. Step 2: Convert to fraction form
    18.78/25.90 = 11.86/x
  3. Step 3: Cross multiply
    18.78x = 25.90 × 11.86
  4. Step 4: Simplify right side
    18.78x = 307.17
  5. Step 5: Solve for x
    x = 307.17/18.78
  6. Step 6: Final answer
    x = 16.36

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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.