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Finding the Fourth Proportional to 12.45, 17.20 and 9.72

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Solution

The fourth proportional to 12.45, 17.20 and 9.72 is: 13.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    12.45 : 17.20 = 9.72 : x
  2. Step 2: Convert to fraction form
    12.45/17.20 = 9.72/x
  3. Step 3: Cross multiply
    12.45x = 17.20 × 9.72
  4. Step 4: Simplify right side
    12.45x = 167.14
  5. Step 5: Solve for x
    x = 167.14/12.45
  6. Step 6: Final answer
    x = 13.42

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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.