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Finding the Fourth Proportional to 28.76, 39.65 and 21.47

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Solution

The fourth proportional to 28.76, 39.65 and 21.47 is: 29.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.76 : 39.65 = 21.47 : x
  2. Step 2: Convert to fraction form
    28.76/39.65 = 21.47/x
  3. Step 3: Cross multiply
    28.76x = 39.65 × 21.47
  4. Step 4: Simplify right side
    28.76x = 851.24
  5. Step 5: Solve for x
    x = 851.24/28.76
  6. Step 6: Final answer
    x = 29.60

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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.