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Finding the Fourth Proportional to 28.51, 39.30 and 20.72

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Solution

The fourth proportional to 28.51, 39.30 and 20.72 is: 28.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.51 : 39.30 = 20.72 : x
  2. Step 2: Convert to fraction form
    28.51/39.30 = 20.72/x
  3. Step 3: Cross multiply
    28.51x = 39.30 × 20.72
  4. Step 4: Simplify right side
    28.51x = 814.19
  5. Step 5: Solve for x
    x = 814.19/28.51
  6. Step 6: Final answer
    x = 28.56

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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.