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Finding the Fourth Proportional to 128.40, 191.60 and 114.73

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Solution

The fourth proportional to 128.40, 191.60 and 114.73 is: 171.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.40 : 191.60 = 114.73 : x
  2. Step 2: Convert to fraction form
    128.40/191.60 = 114.73/x
  3. Step 3: Cross multiply
    128.40x = 191.60 × 114.73
  4. Step 4: Simplify right side
    128.40x = 21,981.31
  5. Step 5: Solve for x
    x = 21,981.31/128.40
  6. Step 6: Final answer
    x = 171.20

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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.