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Finding the Fourth Proportional to 128.95, 178.02 and 105.69

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Solution

The fourth proportional to 128.95, 178.02 and 105.69 is: 145.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.95 : 178.02 = 105.69 : x
  2. Step 2: Convert to fraction form
    128.95/178.02 = 105.69/x
  3. Step 3: Cross multiply
    128.95x = 178.02 × 105.69
  4. Step 4: Simplify right side
    128.95x = 18,815.65
  5. Step 5: Solve for x
    x = 18,815.65/128.95
  6. Step 6: Final answer
    x = 145.91

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.