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Finding the Fourth Proportional to 128.55, 192.79 and 55.43

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Solution

The fourth proportional to 128.55, 192.79 and 55.43 is: 83.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.55 : 192.79 = 55.43 : x
  2. Step 2: Convert to fraction form
    128.55/192.79 = 55.43/x
  3. Step 3: Cross multiply
    128.55x = 192.79 × 55.43
  4. Step 4: Simplify right side
    128.55x = 10,686.35
  5. Step 5: Solve for x
    x = 10,686.35/128.55
  6. Step 6: Final answer
    x = 83.13

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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.