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Finding the Fourth Proportional to 128.48, 192.68 and 51.42

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Solution

The fourth proportional to 128.48, 192.68 and 51.42 is: 77.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.48 : 192.68 = 51.42 : x
  2. Step 2: Convert to fraction form
    128.48/192.68 = 51.42/x
  3. Step 3: Cross multiply
    128.48x = 192.68 × 51.42
  4. Step 4: Simplify right side
    128.48x = 9,907.99
  5. Step 5: Solve for x
    x = 9,907.99/128.48
  6. Step 6: Final answer
    x = 77.12

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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.