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Finding the Fourth Proportional to 28.47, 39.32 and 21.57

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Solution

The fourth proportional to 28.47, 39.32 and 21.57 is: 29.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.47 : 39.32 = 21.57 : x
  2. Step 2: Convert to fraction form
    28.47/39.32 = 21.57/x
  3. Step 3: Cross multiply
    28.47x = 39.32 × 21.57
  4. Step 4: Simplify right side
    28.47x = 848.02
  5. Step 5: Solve for x
    x = 848.02/28.47
  6. Step 6: Final answer
    x = 29.79

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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.