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Finding the Fourth Proportional to 43.20, 64.85 and 21.56

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Solution

The fourth proportional to 43.20, 64.85 and 21.56 is: 32.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    43.20 : 64.85 = 21.56 : x
  2. Step 2: Convert to fraction form
    43.20/64.85 = 21.56/x
  3. Step 3: Cross multiply
    43.20x = 64.85 × 21.56
  4. Step 4: Simplify right side
    43.20x = 1,397.73
  5. Step 5: Solve for x
    x = 1,397.73/43.20
  6. Step 6: Final answer
    x = 32.35

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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.