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Finding the Fourth Proportional to 57.12, 85.71 and 21.06

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Solution

The fourth proportional to 57.12, 85.71 and 21.06 is: 31.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.12 : 85.71 = 21.06 : x
  2. Step 2: Convert to fraction form
    57.12/85.71 = 21.06/x
  3. Step 3: Cross multiply
    57.12x = 85.71 × 21.06
  4. Step 4: Simplify right side
    57.12x = 1,805.05
  5. Step 5: Solve for x
    x = 1,805.05/57.12
  6. Step 6: Final answer
    x = 31.60

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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.