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Finding the Fourth Proportional to 15.55, 21.42 and 12.31

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Solution

The fourth proportional to 15.55, 21.42 and 12.31 is: 16.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.55 : 21.42 = 12.31 : x
  2. Step 2: Convert to fraction form
    15.55/21.42 = 12.31/x
  3. Step 3: Cross multiply
    15.55x = 21.42 × 12.31
  4. Step 4: Simplify right side
    15.55x = 263.68
  5. Step 5: Solve for x
    x = 263.68/15.55
  6. Step 6: Final answer
    x = 16.96

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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.