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Finding the Fourth Proportional to 128.76, 191.79 and 109.08

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Solution

The fourth proportional to 128.76, 191.79 and 109.08 is: 162.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.76 : 191.79 = 109.08 : x
  2. Step 2: Convert to fraction form
    128.76/191.79 = 109.08/x
  3. Step 3: Cross multiply
    128.76x = 191.79 × 109.08
  4. Step 4: Simplify right side
    128.76x = 20,920.45
  5. Step 5: Solve for x
    x = 20,920.45/128.76
  6. Step 6: Final answer
    x = 162.48

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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.