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Finding the Fourth Proportional to 28.39, 42.56 and 21.16

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Solution

The fourth proportional to 28.39, 42.56 and 21.16 is: 31.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.39 : 42.56 = 21.16 : x
  2. Step 2: Convert to fraction form
    28.39/42.56 = 21.16/x
  3. Step 3: Cross multiply
    28.39x = 42.56 × 21.16
  4. Step 4: Simplify right side
    28.39x = 900.57
  5. Step 5: Solve for x
    x = 900.57/28.39
  6. Step 6: Final answer
    x = 31.72

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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.