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Finding the Fourth Proportional to 128.18, 191.85 and 91.51

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Solution

The fourth proportional to 128.18, 191.85 and 91.51 is: 136.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.18 : 191.85 = 91.51 : x
  2. Step 2: Convert to fraction form
    128.18/191.85 = 91.51/x
  3. Step 3: Cross multiply
    128.18x = 191.85 × 91.51
  4. Step 4: Simplify right side
    128.18x = 17,555.37
  5. Step 5: Solve for x
    x = 17,555.37/128.18
  6. Step 6: Final answer
    x = 136.96

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.