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Finding the Fourth Proportional to 128.57, 192.80 and 51.49

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Solution

The fourth proportional to 128.57, 192.80 and 51.49 is: 77.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.57 : 192.80 = 51.49 : x
  2. Step 2: Convert to fraction form
    128.57/192.80 = 51.49/x
  3. Step 3: Cross multiply
    128.57x = 192.80 × 51.49
  4. Step 4: Simplify right side
    128.57x = 9,926.27
  5. Step 5: Solve for x
    x = 9,926.27/128.57
  6. Step 6: Final answer
    x = 77.20

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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.