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Finding the Fourth Proportional to 12.90, 19.28 and 10.85

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Solution

The fourth proportional to 12.90, 19.28 and 10.85 is: 16.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    12.90 : 19.28 = 10.85 : x
  2. Step 2: Convert to fraction form
    12.90/19.28 = 10.85/x
  3. Step 3: Cross multiply
    12.90x = 19.28 × 10.85
  4. Step 4: Simplify right side
    12.90x = 209.04
  5. Step 5: Solve for x
    x = 209.04/12.90
  6. Step 6: Final answer
    x = 16.20

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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.