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Finding the Fourth Proportional to 15.39, 21.29 and 13.08

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Solution

The fourth proportional to 15.39, 21.29 and 13.08 is: 18.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.39 : 21.29 = 13.08 : x
  2. Step 2: Convert to fraction form
    15.39/21.29 = 13.08/x
  3. Step 3: Cross multiply
    15.39x = 21.29 × 13.08
  4. Step 4: Simplify right side
    15.39x = 278.42
  5. Step 5: Solve for x
    x = 278.42/15.39
  6. Step 6: Final answer
    x = 18.09

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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.