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Finding the Fourth Proportional to 65.20, 97.81 and 21.87

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Solution

The fourth proportional to 65.20, 97.81 and 21.87 is: 32.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.20 : 97.81 = 21.87 : x
  2. Step 2: Convert to fraction form
    65.20/97.81 = 21.87/x
  3. Step 3: Cross multiply
    65.20x = 97.81 × 21.87
  4. Step 4: Simplify right side
    65.20x = 2,139.10
  5. Step 5: Solve for x
    x = 2,139.10/65.20
  6. Step 6: Final answer
    x = 32.81

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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.