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Finding the Fourth Proportional to 128.22, 191.47 and 103.87

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Solution

The fourth proportional to 128.22, 191.47 and 103.87 is: 155.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.22 : 191.47 = 103.87 : x
  2. Step 2: Convert to fraction form
    128.22/191.47 = 103.87/x
  3. Step 3: Cross multiply
    128.22x = 191.47 × 103.87
  4. Step 4: Simplify right side
    128.22x = 19,887.99
  5. Step 5: Solve for x
    x = 19,887.99/128.22
  6. Step 6: Final answer
    x = 155.11

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.