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Finding the Fourth Proportional to 28.11, 42.20 and 21.03

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Solution

The fourth proportional to 28.11, 42.20 and 21.03 is: 31.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.11 : 42.20 = 21.03 : x
  2. Step 2: Convert to fraction form
    28.11/42.20 = 21.03/x
  3. Step 3: Cross multiply
    28.11x = 42.20 × 21.03
  4. Step 4: Simplify right side
    28.11x = 887.36
  5. Step 5: Solve for x
    x = 887.36/28.11
  6. Step 6: Final answer
    x = 31.57

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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.