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Finding the Fourth Proportional to 103.68, 156.09 and 81.15

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Solution

The fourth proportional to 103.68, 156.09 and 81.15 is: 122.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.68 : 156.09 = 81.15 : x
  2. Step 2: Convert to fraction form
    103.68/156.09 = 81.15/x
  3. Step 3: Cross multiply
    103.68x = 156.09 × 81.15
  4. Step 4: Simplify right side
    103.68x = 12,666.70
  5. Step 5: Solve for x
    x = 12,666.70/103.68
  6. Step 6: Final answer
    x = 122.17

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.