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Finding the Fourth Proportional to 20.39, 28.15 and 13.12

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Solution

The fourth proportional to 20.39, 28.15 and 13.12 is: 18.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.39 : 28.15 = 13.12 : x
  2. Step 2: Convert to fraction form
    20.39/28.15 = 13.12/x
  3. Step 3: Cross multiply
    20.39x = 28.15 × 13.12
  4. Step 4: Simplify right side
    20.39x = 369.22
  5. Step 5: Solve for x
    x = 369.22/20.39
  6. Step 6: Final answer
    x = 18.11

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1.5x scale

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.