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Finding the Fourth Proportional to 128.61, 191.88 and 115.56

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Solution

The fourth proportional to 128.61, 191.88 and 115.56 is: 172.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.61 : 191.88 = 115.56 : x
  2. Step 2: Convert to fraction form
    128.61/191.88 = 115.56/x
  3. Step 3: Cross multiply
    128.61x = 191.88 × 115.56
  4. Step 4: Simplify right side
    128.61x = 22,173.65
  5. Step 5: Solve for x
    x = 22,173.65/128.61
  6. Step 6: Final answer
    x = 172.41

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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.