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Finding the Fourth Proportional to 128.25, 191.51 and 105.38

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Solution

The fourth proportional to 128.25, 191.51 and 105.38 is: 157.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.25 : 191.51 = 105.38 : x
  2. Step 2: Convert to fraction form
    128.25/191.51 = 105.38/x
  3. Step 3: Cross multiply
    128.25x = 191.51 × 105.38
  4. Step 4: Simplify right side
    128.25x = 20,179.84
  5. Step 5: Solve for x
    x = 20,179.84/128.25
  6. Step 6: Final answer
    x = 157.35

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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.