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Finding the Fourth Proportional to 128.63, 192.47 and 77.31

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Solution

The fourth proportional to 128.63, 192.47 and 77.31 is: 115.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.63 : 192.47 = 77.31 : x
  2. Step 2: Convert to fraction form
    128.63/192.47 = 77.31/x
  3. Step 3: Cross multiply
    128.63x = 192.47 × 77.31
  4. Step 4: Simplify right side
    128.63x = 14,879.86
  5. Step 5: Solve for x
    x = 14,879.86/128.63
  6. Step 6: Final answer
    x = 115.68

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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.