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Finding the Fourth Proportional to 128.98, 192.65 and 128.31

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Solution

The fourth proportional to 128.98, 192.65 and 128.31 is: 191.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.98 : 192.65 = 128.31 : x
  2. Step 2: Convert to fraction form
    128.98/192.65 = 128.31/x
  3. Step 3: Cross multiply
    128.98x = 192.65 × 128.31
  4. Step 4: Simplify right side
    128.98x = 24,718.92
  5. Step 5: Solve for x
    x = 24,718.92/128.98
  6. Step 6: Final answer
    x = 191.65

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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.