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Finding the Fourth Proportional to 15.86, 21.86 and 12.39

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Solution

The fourth proportional to 15.86, 21.86 and 12.39 is: 17.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.86 : 21.86 = 12.39 : x
  2. Step 2: Convert to fraction form
    15.86/21.86 = 12.39/x
  3. Step 3: Cross multiply
    15.86x = 21.86 × 12.39
  4. Step 4: Simplify right side
    15.86x = 270.85
  5. Step 5: Solve for x
    x = 270.85/15.86
  6. Step 6: Final answer
    x = 17.08

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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.