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Finding the Fourth Proportional to 128.66, 192.86 and 77.24

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Solution

The fourth proportional to 128.66, 192.86 and 77.24 is: 115.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.66 : 192.86 = 77.24 : x
  2. Step 2: Convert to fraction form
    128.66/192.86 = 77.24/x
  3. Step 3: Cross multiply
    128.66x = 192.86 × 77.24
  4. Step 4: Simplify right side
    128.66x = 14,896.51
  5. Step 5: Solve for x
    x = 14,896.51/128.66
  6. Step 6: Final answer
    x = 115.78

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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.