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Finding the Fourth Proportional to 20.65, 28.48 and 13.38

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Solution

The fourth proportional to 20.65, 28.48 and 13.38 is: 18.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.65 : 28.48 = 13.38 : x
  2. Step 2: Convert to fraction form
    20.65/28.48 = 13.38/x
  3. Step 3: Cross multiply
    20.65x = 28.48 × 13.38
  4. Step 4: Simplify right side
    20.65x = 381.06
  5. Step 5: Solve for x
    x = 381.06/20.65
  6. Step 6: Final answer
    x = 18.45

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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.