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Finding the Fourth Proportional to 128.75, 192.45 and 105.80

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Solution

The fourth proportional to 128.75, 192.45 and 105.80 is: 158.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.75 : 192.45 = 105.80 : x
  2. Step 2: Convert to fraction form
    128.75/192.45 = 105.80/x
  3. Step 3: Cross multiply
    128.75x = 192.45 × 105.80
  4. Step 4: Simplify right side
    128.75x = 20,360.68
  5. Step 5: Solve for x
    x = 20,360.68/128.75
  6. Step 6: Final answer
    x = 158.14

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.