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Finding the Fourth Proportional to 57.18, 85.81 and 21.11

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Solution

The fourth proportional to 57.18, 85.81 and 21.11 is: 31.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.18 : 85.81 = 21.11 : x
  2. Step 2: Convert to fraction form
    57.18/85.81 = 21.11/x
  3. Step 3: Cross multiply
    57.18x = 85.81 × 21.11
  4. Step 4: Simplify right side
    57.18x = 1,811.45
  5. Step 5: Solve for x
    x = 1,811.45/57.18
  6. Step 6: Final answer
    x = 31.68

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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.