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Finding the Fourth Proportional to 128.35, 191.60 and 115.30

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Solution

The fourth proportional to 128.35, 191.60 and 115.30 is: 172.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.35 : 191.60 = 115.30 : x
  2. Step 2: Convert to fraction form
    128.35/191.60 = 115.30/x
  3. Step 3: Cross multiply
    128.35x = 191.60 × 115.30
  4. Step 4: Simplify right side
    128.35x = 22,091.48
  5. Step 5: Solve for x
    x = 22,091.48/128.35
  6. Step 6: Final answer
    x = 172.12

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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.