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Finding the Fourth Proportional to 70.60, 105.90 and 21.85

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Solution

The fourth proportional to 70.60, 105.90 and 21.85 is: 32.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.60 : 105.90 = 21.85 : x
  2. Step 2: Convert to fraction form
    70.60/105.90 = 21.85/x
  3. Step 3: Cross multiply
    70.60x = 105.90 × 21.85
  4. Step 4: Simplify right side
    70.60x = 2,314.19
  5. Step 5: Solve for x
    x = 2,314.19/70.60
  6. Step 6: Final answer
    x = 32.78

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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.