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Finding the Fourth Proportional to 28.52, 39.40 and 21.28

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Solution

The fourth proportional to 28.52, 39.40 and 21.28 is: 29.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.52 : 39.40 = 21.28 : x
  2. Step 2: Convert to fraction form
    28.52/39.40 = 21.28/x
  3. Step 3: Cross multiply
    28.52x = 39.40 × 21.28
  4. Step 4: Simplify right side
    28.52x = 838.28
  5. Step 5: Solve for x
    x = 838.28/28.52
  6. Step 6: Final answer
    x = 29.39

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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.