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Finding the Fourth Proportional to 13.21, 19.72 and 12.85

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Solution

The fourth proportional to 13.21, 19.72 and 12.85 is: 19.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.21 : 19.72 = 12.85 : x
  2. Step 2: Convert to fraction form
    13.21/19.72 = 12.85/x
  3. Step 3: Cross multiply
    13.21x = 19.72 × 12.85
  4. Step 4: Simplify right side
    13.21x = 253.48
  5. Step 5: Solve for x
    x = 253.48/13.21
  6. Step 6: Final answer
    x = 19.18

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.