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Finding the Fourth Proportional to 128.56, 192.72 and 100

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Solution

The fourth proportional to 128.56, 192.72 and 100 is: 149.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.56 : 192.72 = 100 : x
  2. Step 2: Convert to fraction form
    128.56/192.72 = 100/x
  3. Step 3: Cross multiply
    128.56x = 192.72 × 100
  4. Step 4: Simplify right side
    128.56x = 19,272
  5. Step 5: Solve for x
    x = 19,272/128.56
  6. Step 6: Final answer
    x = 149.91

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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.