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Finding the Fourth Proportional to 28.39, 42.45 and 21.90

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Solution

The fourth proportional to 28.39, 42.45 and 21.90 is: 32.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.39 : 42.45 = 21.90 : x
  2. Step 2: Convert to fraction form
    28.39/42.45 = 21.90/x
  3. Step 3: Cross multiply
    28.39x = 42.45 × 21.90
  4. Step 4: Simplify right side
    28.39x = 929.66
  5. Step 5: Solve for x
    x = 929.66/28.39
  6. Step 6: Final answer
    x = 32.75

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.