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Finding the Fourth Proportional to 105.60, 158.10 and 81.40

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Solution

The fourth proportional to 105.60, 158.10 and 81.40 is: 121.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.60 : 158.10 = 81.40 : x
  2. Step 2: Convert to fraction form
    105.60/158.10 = 81.40/x
  3. Step 3: Cross multiply
    105.60x = 158.10 × 81.40
  4. Step 4: Simplify right side
    105.60x = 12,869.34
  5. Step 5: Solve for x
    x = 12,869.34/105.60
  6. Step 6: Final answer
    x = 121.87

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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.