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Finding the Fourth Proportional to 21.47, 29.63 and 12.85

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Solution

The fourth proportional to 21.47, 29.63 and 12.85 is: 17.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.47 : 29.63 = 12.85 : x
  2. Step 2: Convert to fraction form
    21.47/29.63 = 12.85/x
  3. Step 3: Cross multiply
    21.47x = 29.63 × 12.85
  4. Step 4: Simplify right side
    21.47x = 380.53
  5. Step 5: Solve for x
    x = 380.53/21.47
  6. Step 6: Final answer
    x = 17.72

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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.